CN105722539B - Auxiliary manual injection device and method - Google Patents

Abstract

Various embodiments disclosed herein relate to needle-based syringes that incorporate a force assembly including a storable energy source and a rate control assembly. The force assembly is further configured to allow an injection to be performed using a force during the injection that is greater than the user is able to exert, while also allowing the user to maintain control over the injection process after the stored energy source has been released and the injection has begun, so that the user can increase or decrease the injection rate, or stop the injection. In various embodiments, the force assembly may include a stored energy source based on a spring or gas, and/or may include a rate control assembly based on friction or tension. Also described herein are methods for injecting the formulations using embodiments of the devices described herein.

Description

Auxiliary manual injection device and method

Cross reference to related applications

This application claims priority to U.S. provisional application serial No. 61/903,884, filed on 13/11/2013, the entire contents of which are incorporated herein by reference.

Technical Field

A power-assisted injection device is described herein that allows a user to selectively increase or decrease the injection rate and pause or stop the injection as desired.

Background

The injection of therapeutic agents in hospitals, clinics and home devices is a common procedure, but can sometimes be complex and difficult to perform, even for experienced healthcare personnel. Drawing the therapeutic agent into the syringe and injecting it into the patient requires a certain level of manual power and strength, as well as sufficient visual and mental sensitivity to perform the procedural steps. The risk of needle stick injury also exists throughout all steps of the manual injection procedure. In a home-based environment, these challenges can cause a decrease in patient compliance with a treatment regimen.

However, as the reliance on home injection protocols continues to increase, the challenges of injector injection have become more diverse. For example, patients with physical or cognitive impairments may need to perform such injections without assistance from home healthcare personnel. Furthermore, some injections require a force that is greater than the user can achieve, for example in the case of injectate having a high viscosity. Furthermore, for some drugs, the injection process may cause discomfort associated with the injection rate. In some cases, the user may need to increase the injection rate in order to complete the injection in a shorter time, or may wish to decrease the injection rate or stop the injection, for example to alleviate pain associated with the injection. There is therefore a need for a power assisted injection device that allows the user to both control the stored energy source and provide an amount of user supplied force for injection, and thus increase or decrease the injection rate, or stop the injection as desired.

Disclosure of Invention

Various embodiments disclosed herein relate to needle-based syringes that incorporate a force assembly including a storable energy source and a rate control assembly. The force assembly is further configured to allow an injection to be performed using a force during the injection that is greater than the user is able to exert, while also allowing the user to maintain control over the injection process after the stored energy source has been released and the injection has begun, so that the user can increase or decrease the injection rate, or stop the injection. In various embodiments, the force assembly may include a stored energy source based on a spring or gas, and may include a rate control assembly based on friction or tension. Also described herein are methods for injecting the formulations using embodiments of the devices described herein.

One particular embodiment includes a device for injecting a formulation, the device comprising: a syringe comprising a syringe cavity, a plunger element slidably received in the syringe cavity, and a hollow needle in fluid communication with the syringe cavity, wherein the plunger element is configured to move from a proximal position to a distal position; a force assembly configured to transmit force to the plunger element; and a user-actuated brake assembly configured to reversibly resist movement of the plunger element in at least one intermediate position between the proximal and distal positions. The brake assembly may be biased to prevent movement of the plunger element when in the inactivated state and may allow movement of the plunger element when in the activated state. The brake assembly may be biased by a brake spring to resist movement of the plunger element. The force assembly may include a mechanical spring. The plunger element may also be configured to simultaneously receive a user-applied force that moves the plunger element toward the distal position. The device also includes a housing, wherein the syringe is located in the housing. The housing may be coupled to the plunger element. The housing may be configured to transmit a user-applied force to the plunger element. The brake assembly may include a flexible, elongated brake line. The brake cord may include a releasable friction fit to reversibly resist movement of the plunger element. The releasable friction fit may be provided by a releasable tension in the brake line. The brake assembly may include a rigid friction element. The brake assembly may act on an outer surface of the syringe to reversibly resist movement of the plunger element. The brake assembly may act on a surface fixed relative to the syringe to reversibly resist movement of the plunger element. The brake assembly may include an opening in which the syringe is located. The power assembly may be configured to pull the plunger element to the distal position. The power assembly may be configured to pull the plunger element to the distal position. The power assembly may also be configured to push and pull the plunger element toward the distal position. The syringe may be slidably located in the housing and the syringe configured to move from a retracted position in which the distal tip of the needle is located within the housing toward an extended position in which the distal tip of the needle extends distally of the housing. The device may also include an extendable needle shield, wherein the needle shield may be configured to have a releasably locked, retracted state relative to the syringe and an unlocked state that may be permitted to move toward an extended position relative to the syringe. The device may further comprise an extendable needle shield, wherein the needle shield is configured to have a releasably locked, retracted state relative to the syringe and an unlocked state allowing movement towards an extended position relative to the syringe, and wherein the needle shield is further configured to switch into the unlocked state before the distal end of the needle is extended distally of the housing. The needle shield may also be configured to relock when the needle shield reaches the extended state. In other variations, the device may include an extendable needle shield, wherein the needle shield is configured to have an unlocked extension and a locked extension that allow movement toward a retracted position relative to the syringe. The needle shield may be configured to enter a locked extended state when the needle shield is extended from the retracted state.

One particular embodiment includes a device for injecting a formulation, the device comprising: a syringe comprising a syringe cavity containing a formulation comprising a formulation; and a power assembly configured to act on the syringe to displace the formulation from the syringe cavity, wherein the power assembly comprises a stored energy source and a rate control assembly, wherein the rate control assembly resists the stored energy source acting on the syringe when in a first configuration and allows the stored energy source to act on the syringe when in a second configuration. The rate control assembly may be partially resistant to the stored energy source acting on the injector in the third configuration. The device may also include a housing, wherein the syringe and force assembly are at least partially located within the housing. The rate control assembly may be configured to be switched from the first configuration to the second configuration by application of a distal force on the housing. The switch from the first configuration to the second configuration may be reversible. The rate control assembly may be configured to switch from the second configuration to the first configuration by eliminating or reducing a distal force exerted on the housing. The switch from the second configuration to the first configuration may be reversible. The housing may comprise a proximal housing and a distal housing, and wherein the distal force may be applied to the housing on the proximal housing. The distal housing may include a distal end and a nose at the distal end, and wherein the nose has an expanded shape. The syringe may further include a plunger slidable within the syringe cavity and a needle having a lumen in fluid communication with the syringe cavity, wherein the syringe may be configured such that distal movement of the plunger within the syringe cavity may displace the formulation from the syringe cavity through the lumen of the needle. In the first configuration, the rate control assembly may prevent distal movement of the plunger within the syringe cavity. In the second configuration, the rate control assembly may allow distal movement of the plunger within the syringe cavity. The stored energy source may comprise a spring. The rate control assembly may include a longitudinal axis and the housing may include a longitudinal axis, and the rate control assembly may be configured to be reversibly moved from the first configuration to the second configuration by moving the longitudinal axis of the rate control assembly toward the longitudinal axis of the housing. The stored energy source may comprise a compound spring, wherein the compound spring may comprise a coaxially arranged compression spring and extension spring. The rate control assembly may include a cord that includes at least two portions capable of withstanding different amounts of tension. The stored energy source may include a compressed gas or liquid propellant in a supercritical state. The device is configured such that the rate at which the formulation can be displaced from the syringe can be selectively increased, decreased, or stopped after the plunger has been moved distally relative to an initial position within the syringe cavity. The device may be configured such that distal movement of the plunger within the syringe cavity may require application of a distal force by the user during movement.

One particular embodiment includes a device for injecting a formulation, the device comprising: a syringe comprising a syringe cavity containing a formulation containing a preparation to be injected by application of a distal force on the device by a user; and a force assembly configured to act on the syringe, wherein the force assembly is configured to amplify the distal force applied by the user such that the formulation can be injected using a distal force greater than the force applied by the user to the device, and wherein the force assembly is configured to reduce the rate of injection of the formulation with reduced distal force. The force assembly may be configured to stop injection of the formulation in the event that the user stops applying the distal force to the device. The formulation may be a liquid formulation. The formulation may be a colloidal formulation.

One particular embodiment includes a device for injecting a formulation, the device comprising: a syringe comprising a syringe cavity, a plunger element slidably received within the syringe cavity, and a hollow needle in fluid communication with the syringe cavity, wherein the plunger is configured to move from a proximal position to a distal position; a pressurized gas assembly having a user-actuated valve opening biased to a closed state; and a flow path between the valve opening and the pressurized region, wherein the flow path is non-linear. The pressurized gas assembly may be configured to apply a force to the surface at a fixed position relative to the plunger to move the plunger from the proximal position to the distal position. The plunger may also be configured to simultaneously receive a user-applied force that moves the plunger element toward the distal position. The device may further comprise a housing, wherein the syringe may be at least partially located in the housing. The housing may be configured to transmit a user-applied force to the plunger. The housing may be configured to transmit a user-applied force to the valve opening. The valve opening may be configured to be opened by a force applied to the housing by a user. The syringe may be slidably located in the housing and the syringe may be configured to move from a retracted position in which the distal tip of the needle is located within the housing toward an extended position in which the distal tip of the needle projects distally of the housing. The device may also include an extendable needle shield, wherein the needle shield may be configured to have a releasably locked, retracted state relative to the syringe and an unlocked state that may be permitted to move toward the extended position relative to the syringe. The device may further comprise an extendable needle shield, wherein the needle shield may be configured to have a releasably locked, retracted state relative to the syringe and an unlocked state that may allow movement towards the extended position relative to the syringe, and wherein the needle shield may be further configured to switch into the unlocked state before the distal end of the needle extends distally of the housing. The needle shield may also be configured to relock when the needle shield reaches the extended state. The pressurized region may be configured to have a variable volume.

One particular embodiment includes a device for injecting a formulation, the device comprising a housing and a syringe located within the housing, wherein the housing comprises a needle shield having an activated configuration and an inactivated configuration, wherein the needle shield is biased from a retracted position toward an extended position when in the activated configuration, and wherein the needle shield is switched from the inactivated configuration to the activated configuration by distal movement of the syringe relative to at least a portion of the housing. The syringe may include a needle and the syringe may be slidably located in the housing and may be configured to move from a retracted position in which the distal tip of the needle is located within the housing toward an extended position in which the distal tip of the needle extends distally of the housing. The needle shield may be switched from the unactivated configuration to the activated configuration before the distal tip of the needle extends distally of the housing. The needle shield may be configured to be maintained in the retracted position by a proximal force on the needle shield after switching to the activated configuration. The needle shield may also be configured to be locked in the extended position once moved to the extended position.

One particular embodiment includes a device for injecting a formulation, the device comprising: a housing having a longitudinal axis; a syringe containing a formulation within a housing; a plunger slidable within the syringe, the plunger configured to be movable between a proximal position and a distal position, wherein moving the plunger toward the distal position displaces the formulation from the injection; a occluder having a longitudinal axis and comprising an interior cavity through which a syringe is positioned, wherein the occluder is configured to be movable between a first configuration in which the longitudinal axis of the occluder is offset from the longitudinal axis of the housing and a second configuration in which the longitudinal axis of the occluder is offset from the longitudinal axis of the housing to a lesser extent than the first configuration; and a spring in contact with the occluder, the spring configured to bias the plunger toward the distal position via the occluder when the occluder is in the second configuration. A spring may bias the occluder toward the first configuration. The syringe may be configured to be movable relative to the housing between a proximal position and a distal position. The occluder may be configured to move between the first configuration and the second configuration by moving the actuation rod between a first position out of contact with the occluder and a second position in contact with the occluder. The occluder may be configured to be movable between a first configuration and a second configuration by applying a distal force on the housing. The spring may exert a distal force on the occluder. The distal force on the occluder from the spring may oppose the proximal friction force when the occluder is in the first configuration. The device may further comprise a retractable needle shield configured to be movable between a retracted position and an extended position. The device may also include a dose tip indicator movable between an unactuated configuration and an actuated configuration.

One particular embodiment may include a device for injecting a formulation, the device comprising: a housing; a syringe located within the housing, wherein the syringe contains a formulation; a plunger configured to slidably move between a proximal position and a distal position; a spring configured to bias the plunger toward the distal position; and a cord configured to reversibly switch between a tensioned configuration and a tension-relieving configuration, wherein the cord is configured to bias the plunger toward the proximal position when in the tensioned configuration. The plunger may be configured to remain fixed relative to the syringe when the cord is in the tensioned configuration. The plunger may be configured to move toward the distal position when the cord is in the tension relief configuration. The plunger may include a distal end, and the cord may be configured to apply a proximal force to the distal end of the plunger when the cord is in the tensioned configuration. The spring may be configured to pull the plunger toward the distal position.

One particular embodiment may include a device for injecting a formulation, the device comprising: a housing; a syringe located within the housing; and a dose tip indicator, wherein the dose tip indicator has an inactivated configuration and an activated configuration, and wherein the appearance of the dose tip indicator is different in the inactivated configuration and the activated configuration. The syringe may further include a syringe cavity and a plunger slidably received in the syringe cavity, and a hollow needle in fluid communication with the syringe cavity, wherein the plunger may be configured to move from a proximal position to a distal position, and wherein the dose tip indicator is moved from the inactivated configuration to the activated configuration by movement of the plunger toward the distal position.

One particular embodiment may include a method for injecting a formulation using a device comprising: a syringe comprising a syringe cavity, a housing with the syringe located therein, a plunger slidably received in the syringe cavity, and a hollow needle in fluid communication with the syringe cavity, wherein the plunger is configured to move from a proximal position to a distal position; a force assembly configured to transmit force to the plunger; and a user-actuated brake assembly configured to reversibly resist movement of the plunger in at least one intermediate position between the proximal and distal positions, the method comprising: applying a force to the housing, wherein the force causes the force assembly to transmit force to the plunger to move the plunger toward the distal position; and reducing a force applied to the housing when the plunger is in the intermediate position, wherein reducing the applied force causes the brake assembly to reduce the force transmitted to the plunger by the force assembly. The housing may include a proximal housing and a distal housing, and wherein applying force to the housing includes applying distal force to the proximal housing. The application of force to the housing may also move the brake assembly from an inactivated state to an activated state, wherein the brake assembly may be biased to prevent movement of the plunger element when in the inactivated state and may allow movement of the plunger element when in the activated state. The method may further include re-applying force to the housing, wherein the force may cause the force assembly to transmit force to the plunger to move the plunger toward the distal position.

One particular embodiment includes a device for injecting a formulation, the device comprising: a housing having a longitudinal axis; a syringe containing the formulation within a syringe cavity, wherein the syringe is located within the housing; a plunger slidable within the syringe, the plunger configured to be movable between a proximal position and a distal position, wherein moving the plunger toward the distal position displaces the formulation from the syringe; and a spring in contact with the syringe, the spring configured to bias the plunger toward the biased distal position, wherein the plunger includes a brake pad configured to be reversibly movable between a first configuration and a second configuration, wherein the brake pad generates friction in the second configuration to resist movement of the plunger. The brake pad may be configured to be movable from a first configuration to a second configuration by moving radially outward. The device may also include a stopper located within the plunger and movable within the plunger between a proximal position and a distal position, wherein the stopper is configured such that moving the stopper from the distal position to the proximal position moves the brake pad from the first configuration to the second configuration. The stop may be biased toward the detection position. The stopper may be configured to be movable between a proximal position and a distal position by application of a distal force on the housing. The device may further comprise a retractable needle shield configured to be movable between a retracted position and an extended position. The device may also include a dose tip indicator movable between an unactuated configuration and an actuated configuration.

Drawings

Fig. 1 shows a perspective view of an embodiment of an injection device.

Fig. 2A-2N are longitudinal cross-sectional views of the embodiment of the injection device of fig. 1 in various stages of use. Fig. 2A-2B show two orthogonal cross-sectional views of the device prior to use. Fig. 2C-2D show two orthogonal cross-sectional views of the device with the rigid needle shield and cap removed. Figures 2E-2F show two orthogonal cross-sectional views of the device with the syringe partially moved toward the extended position. Fig. 2G-2H show two orthogonal cross-sectional views of the device with the syringe in the extended position. Fig. 2I-2J show two orthogonal cross-sectional views of the device with the plunger partially moved toward a distal position within the syringe cavity. Fig. 2K-2L are two orthogonal cross-sectional views of the device with the plunger moved to a distal position within the syringe cavity. Fig. 2M-2N show two orthogonal cross-sectional views of the device with the needle shield extended.

Fig. 3A-3F are longitudinal cross-sectional views of the distal portion of the injection device of fig. 1 showing the needle shield in a retracted position (fig. 3A-3B), unlocked from the retracted position (fig. 3C-3D), and in an extended position (fig. 3E-3F).

Fig. 4A-4C show longitudinal cross-sectional views of a proximal portion of the injection device of fig. 1, showing the dose tip indicator in an unactuated configuration (fig. 4A), a released configuration (fig. 4B), and an actuated configuration (fig. 4C). Fig. 4D-4E show cut-away elevational side views of a proximal portion of another embodiment of an injection device showing another example of a dose tip indicator in an unactivated configuration (fig. 4D) and an activated configuration (fig. 4E).

Fig. 5 shows an exploded perspective view of the injection device 100.

Fig. 6A-6B are orthogonal longitudinal cross-sectional views of a central portion of the syringe of fig. 1 showing an interlock device.

Fig. 7 shows a perspective view of the stored energy source of the injection device of fig. 1.

Fig. 8A-8B are side perspective views of the rate control assembly of the injection device of fig. 1.

Fig. 9 shows a longitudinal cross-sectional view of the rate control assembly.

Fig. 10 is a perspective view of another embodiment of an injection device.

11A-11B are elevational side views of the injection device of FIG. 10 with the cap installed and removed, respectively.

Fig. 12A-12F are longitudinal cross-sectional views of the embodiment of the injection device of fig. 10 in various stages of use. Fig. 12A shows the device before use. Fig. 12B shows the device with the rigid needle shield and cap removed. Fig. 12C shows the device with the syringe in the extended position. Fig. 12D shows the device with the plunger moved to a distal position within the syringe cavity. Fig. 12E shows the device with the dose tip indicator in an activated configuration. Fig. 12F shows the device with the needle shield extended.

Fig. 13A-13D show longitudinal sectional views (fig. 13A and 13C) and cut-away elevational side views (fig. 13B and 13D) of the distal portion of the injection device of fig. 10 showing the needle shield in the retracted position and the extended position, respectively.

Fig. 14A-14B are a longitudinal cross-sectional view and a cut-away elevational side view, respectively, of a proximal portion of the injection device of fig. 10, showing the dose tip indicator in an activated configuration.

Fig. 15 shows a perspective view of the syringe and syringe barrel of the injection device of fig. 10.

Fig. 16A-16B show a cut-away elevational side view and a longitudinal cross-sectional view, respectively, of the ram and force assembly of the injection device of fig. 10. Fig. 16C-16D show perspective views of the base stop cover and the ram interlock, respectively.

Fig. 17 is a perspective view of a force assembly of the injection device of fig. 10.

Fig. 18 is a perspective view of another embodiment of an injection device.

Fig. 19A-19G show longitudinal cross-sectional views of the embodiment of the injection device of fig. 17 at various stages of use. Fig. 19A shows the device before use. Fig. 19B shows the device with the rigid needle shield and cap removed. Figure 19C shows the device with the syringe in a partially extended position. Figure 19D shows the device with the syringe in the fully extended position. Fig. 19E shows the device with the plunger partially moved toward the distal position within the syringe cavity. Fig. 19F shows the device with the plunger in the distal position within the syringe cavity. Fig. 19G shows the device with the needle shield extended.

Fig. 20A shows a longitudinal cross-sectional view of the pressure path of the injection device of fig. 18, with arrows indicating the path. Fig. 20B shows an enlarged view of a portion of the pressure path of fig. 20A. Fig. 20C shows a longitudinal cross-sectional view of the vent path of the injection device of fig. 18.

Fig. 21 shows an illustrative graph of the force required for a user to perform an injection using an injection device similar to the injection device of fig. 1.

Fig. 22 shows an illustrative graph of the force required for a user to perform an injection using an injection device similar to that of fig. 10.

Fig. 23 shows a graph of illustrative load multiplication factors for an injection device similar to the injection device of fig. 18.

Figure 24A shows a schematic representation of a model of a two-dimensional friction-based bite having two contact points. Figure 24B shows a schematic representation of a model of a friction-based bite having three contact points.

Fig. 25A-25C show schematic representations of the configurations of the proximal housing and the distal housing of the injection device.

Fig. 26 is a perspective view of another embodiment of an injection device.

Fig. 27A-27H show longitudinal cross-sectional views of the embodiment of the injection device of fig. 26 in various stages of use. Fig. 27A shows the device before use. Fig. 27B shows the device with the syringe in a partially extended position. Fig. 27C shows the device with the syringe in the fully extended position. Fig. 27D shows the device with the ram in contact with the seal. Fig. 27E shows the device with the plunger partially moved toward a distal position within the syringe cavity. Fig. 27F shows the device with the dose tip indicator in an activated configuration. Fig. 27G shows the device with the plunger in a distal position within the syringe cavity. Fig. 27H shows the device with the needle shield extended.

Fig. 28A, 28B, and 28C illustrate the distal portion of the injection device of fig. 26 with the needle safety assembly in an initial extended configuration, a retracted configuration, and a locked extended configuration, respectively.

Fig. 29A, 29B and 29C show perspective views of the needle safety assembly, the interlocking ring and the shield lock ring, respectively, of the injection device of fig. 26.

Fig. 30 shows a perspective view of the ram of the injection device of fig. 26.

Fig. 31 shows an illustrative graph of the force required for a user to perform an injection using an injection device similar to that of fig. 26.

Detailed Description

In general, the injection devices described herein may include a housing that may house a syringe and a power assembly. Generally, the housing may include a proximal housing and a distal housing. The proximal housing and the distal housing may be configured to slidably fit together to form a variable sized cavity. The syringe and force assembly may be located within a cavity formed by the proximal housing and the distal housing, and a force applied to the housing may be translated into a force on the syringe and/or force assembly to cause an injection to be performed. In some variations, the housing may include certain safety features, such as a retractable needle safety assembly to limit accidental needle stick, and/or an indicator to indicate the progress or completion of an injection.

The syringe may be located within the housing and may include: a syringe body defining a syringe cavity and a seal slidably disposed within the syringe cavity, the seal defining a reservoir that can hold a formulation containing a therapeutic or diagnostic agent; a ram including a plunger slidably engaged within the syringe cavity; and a needle at the distal end of the syringe body. The needle may be configured to pierce tissue of a patient receiving an injection and may have a lumen through which the contents of the reservoir are delivered to the tissue of the patient. Distal movement of the seal within the syringe cavity displaces the contents of the reservoir through the lumen of the needle.

The force application assembly may include a stored energy source and a rate control assembly. The stored energy source, when released, may be configured to transmit a force to displace the contents of the syringe through the lumen of the needle and into the patient. In some variations, the force input by the user on the device may work in conjunction with the stored energy source to also provide a force to displace the reservoir contents. In still other variations, the stored energy source may be configured to accomplish this by causing the plunger or seal to move distally within the syringe cavity. The rate control assembly may limit or inhibit displacement of the contents of the reservoir of the injector caused by the stored energy source. In some variations, the rate control assembly may be configured to accomplish this by limiting or inhibiting distal movement of the plunger or seal within the syringe cavity. The rate control assembly is selectively and reversibly movable between an open configuration and a closed configuration; in the closed configuration, the rate control assembly may limit or restrict the stored energy source from causing distal movement of the seal within the syringe cavity. The stored energy source of the power assembly and the rate control assembly may together allow a user (patient or another person) to intuitively guide the injection process by guiding the injection by pressing the injection device against the patient's skin, but the power assembly may supply a supplemental injection force (or in some variations, the full injection force) so that the user does not have to provide all of the force required to perform an injection.

As used throughout this specification, the term "proximal" refers to a direction away from the needle of the syringe. The term "distal" refers to the direction of the needle of the syringe.

One embodiment of an injection device 100 is shown in fig. 1 and 2A-2N and includes a housing 102 that houses a syringe 104 and a power assembly 106. In some embodiments, the housing 102 may include a proximal housing 108 and a distal housing 110. As described above, the proximal housing 108 and the distal housing 110 may be configured to slidably fit together to form the cavity 146. The syringe 104 and force assembly 106 may be located within the cavity 146. It should be appreciated that although the distal housing 110 is shown in fig. 1 and 2A-2N as slidably fitting within the proximal housing 108, in other variations, the proximal housing may be slidably fitting within the distal housing. In still other variations, the housing may comprise only a proximal housing from which the syringe protrudes distally, or only a distal housing on the proximal end of which the syringe or another actuator protrudes distally or is otherwise present. The housing 102 may be configured to move between an extended configuration (shown in fig. 1 and 2A-2D) and a compressed configuration or toward a compressed configuration (shown in fig. 2K-2N) through a range of intermediate configurations (e.g., the configurations shown in fig. 2G-2J) by moving the proximal housing 108 distally relative to the distal housing 110. In the retracted configuration, proximal housing 108 is pushed through distal housing 110, or otherwise overlaps or nests with distal housing 110, and achieves a shorter overall housing length. In some variations, the length of the housing 102 may be less than about 150mm, about 160mm, about 170mm, about 180mm, about 190mm, or about 200mm when in the extended configuration. In other variations, the length of the housing 102 may be greater than about 200 mm. In some variations, the length of the housing 102 when in the extended configuration may be about 150mm to 155mm, about 155mm to 160mm, about 160mm to 165mm, or about 165mm to about 170 mm.

In some variations, the housing 102 may include one or more elements for preventing or inhibiting the housing 102 from moving back toward the extended configuration once initial compression has begun. For example, the housing 102 may include a one-way ratchet mechanism between the proximal housing 108 and the distal housing 110. As another example, distal housing 110 may include a groove (not shown) extending around its circumference. The groove may have a distal side orthogonal to the surface of distal housing 110 and a proximal side angled proximal side. An elastomeric ring (e.g., an O-ring) (not shown) may be located in the groove. Due to the shape of the groove, if the proximal housing 108 is moved proximally relative to the distal housing 110 (i.e., the housing 102 is moved toward the extended configuration), the elastomeric ring may be pulled along the proximal face, preventing further movement. As yet another example, the injection device 100 may include tines (not shown) fixed and distally inclined relative to the distal housing 110 that may travel along the inside of the proximal housing 108. In some variations, the tines may travel along grooves on the inside of the proximal housing 108. The tines may be configured to travel proximally relative to the proximal housing 108 as the proximal housing 108 moves distally, but the tines may not be able to move distally relative to the proximal housing 108 and thus may prevent the housing 108 from moving toward the extended configuration. In some variations, the tines may be attached to or integral with a syringe barrel 430 (described below). In some of these variations, the tines may be attached to or integral with a proximal lip 454 of the syringe sleeve 430 (described below). In some variations, the proximal housing 108 and/or the distal housing 110 may include one or more elements to prevent rotation of the proximal housing 108 and the distal housing 110 relative to each other, such as a blocking (wedging) mechanism described in more detail below. In other variations, the proximal housing 108 and the distal housing 110 may be rotatable relative to one another.

Distal housing 110 may also include a nose 116 at distal end 114, and nose 116 may, but need not, have a tapered shape as shown in fig. 1 and 2A-2N. In still other variations, the nose portion may generally maintain the same size and/or shape along its longitudinal length as the remainder of the distal housing. Alternatively, the nose portion may have an expanded shape, wherein the nose portion has a larger cross-sectional shape than the rest of the distal housing and/or the proximal housing. In some variations, this expanded shape may help a user maintain the injection device 100 in a position perpendicular to the surface of the injection site, a sliding of the injection device 100 as a download pressure is applied by the user, and/or may help allow the tissue to remain relatively flat during the injection process. In some variations, the expanded shape may be a gradual outward expansion of the nose, one illustrative example of which is shown in fig. 25A; in other variations, the nose may include a flat at its distal end having a larger cross-sectional shape (e.g., flat, disk-shaped, oval, elliptical, etc.) than the remainder of the distal and/or proximal shells, one illustrative example of which is shown in fig. 25B. These portions of the nose may be symmetrical about the distal housing, or in other variations it may be asymmetrical about the distal housing. Additionally or alternatively, the proximal housing may include a flared portion at its distal end having a larger cross-sectional shape than the rest of the proximal housing, one illustrative example of which is shown in fig. 25C. This may assist the user in gripping and/or applying force to the proximal housing.

The nose 116 may include a distal opening 112 at its distal end 158, and the needle 406 of the syringe 104 may extend through the distal opening 112, as described below. In some variations, nose 116 may be a separate component of distal housing 110, while in other variations it may be integral with distal housing 110. Similarly, the proximal housing 108 has an end cap 118 at its proximal end 120. In some variations, the end cap 118 may be a separate component of the proximal housing 108, while in other variations it may be integral with the proximal housing 108. The proximal housing 108 may optionally further include a grip (not shown), which may be configured to enhance the user's ability to remain on the proximal housing 108 or to squeeze the proximal housing 108. In some variations, the grip portion may have an ergonomic shape and/or material, such as a rubber grip, that may improve the user's ability to remain on the proximal housing 108 or squeeze the proximal housing 108. Although shown in fig. 1 and 2A-2N as each having a generally cylindrical shape, the proximal housing 108 and the distal housing 110 may have any suitable shape (e.g., having an elliptical cross-section, an oblong cross-section, an oval cross-section, a square cross-section, a rectangular cross-section, a triangular cross-section, etc.). In some variations, the maximum diameter (or maximum distance transverse to the longitudinal axis) of the housing 102 may be less than about 20mm, about 22mm, about 24mm, about 26mm, about 28mm, about 30mm, about 32mm, about 34mm, about 36mm, about 38mm, or about 40 mm. In some variations, the maximum diameter of the housing (or maximum distance transverse to the longitudinal axis) may be about 20mm to 25mm, about 25mm to about 30mm, about 30mm to 35mm, or about 35mm to about 40 mm. In some variations, the proximal housing 108 and/or the distal housing 110 may optionally include one or more anti-roll elements (not shown). In some variations, the anti-roll elements may comprise a planar area on the outside of the proximal housing 108. In some variations, rolling of the housing 102 may be prevented by the housing 102 having a non-circular cross-sectional shape such as the elliptical shapes described above or other non-circular shapes or by the rigid needle shield (described below) having an asymmetric shape. Proximal housing 108 and distal housing 110 may comprise any suitable material, such as, but not limited to, one or more plastic or metallic materials.

In some variations, at least a portion of the distal housing 110 may include a viewing area 124 that allows the syringe 104 to be viewed from outside the housing 102. In some variations, this may allow the user to visually monitor the progress or completion of the injection (e.g., by observing the position of the syringe or seal within the syringe cavity in variations where the syringe body also includes a viewing area or is otherwise transparent or translucent (e.g., due to being constructed of a transparent or translucent material such as glass or plastic)). In other variations, both the proximal housing 108 and the distal housing 110 may include a viewing area, only the proximal housing 108 may include a viewing area, or both the proximal housing 108 and the distal housing 110 may not include a viewing area. The viewing area (e.g., viewing area 124) may comprise a translucent or transparent material such as, but not limited to, glass or plastic. In other variations, the viewing region (e.g., viewing region 124) may be an opening (e.g., an opening in distal housing 110). In other variations, the viewing area may be used as an opening (opened or covered) in place of the syringe component of the device for recycling. In some variations, the viewing region may extend around the entire circumference of the proximal housing 108 and/or the distal housing 110, as shown in fig. 1. In some variations, the viewing area may include substantially all of the distal housing 110, not including the nose 116, as shown in fig. 1. In other variations, the viewing region may extend around a portion of the circumference of the proximal housing and/or the distal housing.

In some variations, the housing 102 may optionally further include a cover. Fig. 2A-2B show two orthogonal cross-sectional views of the injection device 100 with the cap 148 attached prior to use. The cap 148 may be configured to slidably fit over the distal housing 110 and may cover the distal opening 112 of the nose 116. The cover 148 may be removed by applying a force to separate the cover 148 from the remainder of the housing 102. In some variations, this may be accomplished by holding the proximal housing 108 with one hand and holding the cap 148 with the other hand and pulling in the opposite direction. In some variations, the cap 148 may also be used to remove the rigid needle shield 422. The cap 148 may be connected with the rigid needle shield 422 in any suitable manner such that removal of the cap also removes the rigid needle shield 422. For example, the cap 148 may include an inside proximal tab that may fit around the outside of the rigid needle shield 422. The proximal tab may be generally cylindrical, but may have other shapes. The proximal tab may include one or more inwardly facing lips that may fit within a recess or hook (or recesses or hooks) on the outer side of the rigid needle shield 422. When the cap 148 is separated from the rest of the housing 102, the rigid needle shield 422 may also separate from the syringe 104 due to forces on the rigid needle shield 422 from the inward facing lip. In some variations, the proximal tab may be flexible (e.g., due to a cut-out) to allow the cap to be mounted over the distal housing 110 and the rigid needle shield 422. In some variations, the cover may include a viewing area that may coincide with a viewing area of the distal housing when the cover is attached to the remainder of the housing.

Fig. 2A-2N show longitudinal cross-sectional views of the injection device 100 of fig. 1 at various stages of use. Fig. 2A-2B show two orthogonal cross-sectional views of the device prior to use. Fig. 2C-2D show two orthogonal cross-sectional views of the device with the rigid needle shield and cap removed. Figures 2E-2F show two orthogonal cross-sectional views of the device with the syringe partially moved toward the extended position. Fig. 2G-2H show two orthogonal cross-sectional views of the device with the syringe in the extended position. Fig. 2I-2J show two orthogonal cross-sectional views of the device with the plunger partially moved toward a distal position within the syringe cavity. Fig. 2K-2L are two orthogonal cross-sectional views of the device with the plunger moved to a distal position within the syringe cavity. Fig. 2M-2N show two orthogonal cross-sectional views of the device with the needle shield extended. The nose 116 may include a needle safety assembly 200. In some variations, the needle safety assembly 200 may include the extendable needle shield 202, the biasing element 218, and the locking assembly 226 that protect the needle 406 after an injection is completed or terminated. The needle safety assembly 200 is movable between a retracted position (shown in fig. 1, 2A-2L, and 3A-3D) and an extended position (shown in fig. 2M-2N and 3E-3F). In the retracted position, the needle shield 202 may allow the needle 406 of the syringe 104 to be exposed when the syringe 104 is in the extended position, as described in detail below. Thus, in the retracted position, the distal end 212 of the needle shield 202 may be located proximal to the distal tip 424 of the needle 406 when the syringe 104 is in the extended position. In the extended position, the needle shield 202 may shield the needle 406 from exposure when the syringe 104 is in the extended position; for example, the needle shield 202 may prevent insertion of the needle 406 into tissue of the patient or prevent contact between the needle 406 and the tissue. Thus, in the extended position, the distal end 212 of the needle shield 202 may be located distal to the distal tip 424 of the needle 406 when the syringe 104 is in the extended position. In some variations, the displacement of the needle shield 202 between the retracted position and the extended position may be about 6mm to 8mm, about 8mm to 10mm, about 10mm to 12mm, about 12mm to 14mm, or about 14mm to 16 mm.

As shown in fig. 3A-3D, the needle shield 202 may be slidably engaged within the nose 116. In the variation shown in fig. 3A-3F, when the needle safety assembly 200 is in the retracted position, the distal end 212 of the needle shield 202 may be flush with the distal end 158 of the nose 116, while in the extended position, the distal end 212 of the needle shield 202 may be located distal to the distal end 158 of the nose 116. It should be appreciated that in other variations, the distal end 212 of the needle shield 202 may be located proximal to the distal end 158 of the nose 116 in the retracted position, or it may be located distal to the distal end 158 of the nose 116 in other variations in the retracted position.

The needle shield 202 may have a proximal opening 204 and a distal opening 206, with a lumen 208 extending between the proximal opening 204 and the distal opening 206. The needle shield 202 can have a longitudinal axis 210 that is aligned with the longitudinal axis 144 of the housing 202. While the needle shield 202 is shown in fig. 3A-3F as having a cylindrical shape, it should be appreciated that the needle shield can have other shapes (e.g., an elliptical cross-section, an oblong cross-section, an oval cross-section, a square cross-section, a rectangular cross-section, a triangular cross-section, etc.). In some variations, the needle shield 202 may optionally include a stop (not shown) to prevent the needle shield 202 from separating from the nose 116 (e.g., to prevent the needle shield 202 from sliding distally away from the nose 116 and separating from the nose 116). Additionally or alternatively, the needle shield 202 may include a distal lip 216 to retain a biasing element 218 described below. In some variations, the needle shield 202 may comprise a plastic material, but it should be appreciated that the needle shield 202 may comprise any suitable material. The needle shield 202 may optionally be opaque, translucent, or transparent. The needle shield may also optionally include holes or cutouts to allow partial visualization of the needle during or after an injection procedure.

The biasing element 218 may be configured to bias the needle safety assembly 200 toward the extended position. The biasing element 218 may have a compressed configuration and an extended configuration. The biasing element 218 may be in a compressed configuration when the needle safety assembly 200 is in the retracted configuration, and the biasing element 218 may be in an extended configuration when the needle safety assembly 200 is in the extended position. In some variations, the biasing element 218 may include a compression spring 220. When the compression spring 220 is in the compressed configuration, the compression spring 220 may be connected or in contact with a portion of the distal housing 110 or nose 116 at its proximal end 222 and a portion of the needle shield 202 at its distal end 224. The biasing element 218 (e.g., compression spring 220) may thus bias the needle shield 202 distally away from the distal housing 110 and nose 116 through the distal opening 112 of the nose 116. In a variation shown in fig. 3A-3F, the compression spring 220 may have a cylindrical shape and may be nested within the lumen 208 of the needle shield 202. A proximal end 222 of the compression spring 220 may contact the ledge 156 extending radially inward from the distal end 114 of the distal housing 110, while a distal end 224 of the compression spring 220 may contact the lip 216 extending radially inward from the needle shield 202. While the lip 216 is shown in fig. 3A-3F as being located at the distal end 212 of the needle shield 202, it should be appreciated that in other variations the lip may extend from a location proximal to the distal end 212 of the needle shield 202. In some variations, proximal end 222 of compression spring 220 may be fixedly attached to distal end 114 of distal housing 110, but it need not be (e.g., it may rest against distal end 114 of distal housing 110 but not attached). Similarly, in some variations, the distal end 224 of the compression spring 220 may be fixedly attached to the needle shield 202, but it need not be (e.g., it may rest against a portion of the needle shield 202 but not be attached). It should be appreciated that in other variations, the biasing element 218 may not include the compression spring 220 and may instead include other forms of biasing elements (e.g., extension springs, torsion springs, etc.) configured to bias the needle shield 202 distally away from the distal housing 110. In some variations, the biasing element 218 may provide a biasing force of about 1N, about 2N, about 3N, about 4N, about 5N, about 6N, about 7N, or about 8N.

The locking assembly 226 can maintain the needle shield 202 in the retracted position and/or the extended position. In some variations, the locking assembly 226 may include one or more latches 228 that may be configured to connect the needle shield 202 with the syringe 104. While in the embodiment of fig. 3A-3F, the locking assembly 226 may include four latches 228 evenly spaced about the needle shield 202, it should be appreciated that in other variations, the locking assembly 226 may include more or less latches and may have different orientations (e.g., one, two, three, five, or six latches, etc., which may be evenly or unevenly spaced from one another). In some variations, the latch 228 may be integral with the needle shield 202. The latches 228 may each include an elongate portion 230 extending proximally from the needle shield 202 and a tab 234 extending from the elongate portion 230. In some variations, the elongated portion 230 may have different lengths. The elongate portion 230 can extend proximally from the proximal opening 204 of the needle shield 202, and the tabs 234 can extend inwardly from the proximal end of the elongate portion 230. As shown in fig. 3A-3B, the latch 228 may be configured to mate with a syringe sleeve 430 (described below) such that the latch 228 prevents movement of the needle shield 202 relative to the distal housing 110 when mated. The syringe sleeve 430 may include four proximal slots 168 that may be positioned on the syringe sleeve 430 such that the needle shield 202 may be in the retracted position when the tabs 234 of the latch 228 mate with the proximal slots 168. When the tabs 234 are mated with the proximal slot 168, the elongated portion 230 of the latch 228 may be flush with the outer surface 458 of the syringe sleeve 430 and the tabs 234 of the latch 228 may be radially inserted into the proximal slot 168. The locking assembly 226 may resist distal movement due to the biasing force from the biasing element 218 due to the proximally directed force applied to the distal surface of the tab 234 by the distal surface of the proximal slot 168.

As shown in fig. 3C-3D, the locking assembly 226 may be configured such that the needle shield 202 may be unlocked from the retracted position by distal movement of the syringe 104 (e.g., the locking assembly 226 may no longer hold the needle shield 202 in the retracted position). In some variations, the tabs 234 may be configured such that they may be released from the proximal slots 168 by distal movement of the syringe 104 relative to the syringe barrel 430. For example, in the variation shown in fig. 3A-3F, the tab 234 may have a triangular, proximally tapering shape. Thus, as the syringe 104 is moved distally within the syringe sleeve 430, the distal end 418 of the outer surface 468 of the syringe body 405 may engage the inner surface 236 of the tab 234 protruding through the proximal slot 168. As the outer surface 468 of the syringe body 402 continues to slide along the inner surface 460 of the syringe sleeve 430 (described below), the outer surface 468 of the syringe body 402 gradually pushes the tabs 234 further radially out of the proximal slots 168. Once the outer surface 468 of the syringe body 402 has fully radially protruded the tab 234 from the proximal slot 168, the tab 234 may no longer mate with the proximal slot 168 and may no longer prevent distal movement of the needle shield 202 relative to the distal housing 110. It should be appreciated that while the latch in the embodiment of fig. 3A-3F is coupled to (or integral with) the needle shield 202 and fits within a groove in the syringe sleeve 430, in other variations, the latch may be coupled to (or integral with) the syringe sleeve and may fit within a groove in the needle shield. For example, the inner surface of the syringe barrel may comprise inwardly facing tabs which may extend inwardly through slots in the needle shield so that they may project radially within the inner surface of the syringe barrel. As in the embodiment of fig. 3A-3F, distal movement of the syringe may cause the outer surface of the syringe body to push the tabs radially outward through the slots to an extent sufficient that the tabs no longer prevent distal movement of the needle shield relative to the distal housing.

When the needle shield 202 is unlocked from the retracted position, the needle shield 202 can be moved from the retracted position to the extended position if a force (e.g., a biasing force from the biasing element 218) configured to urge the needle shield 202 from the retracted position to the extended position is subsequently applied. However, a force configured to urge the needle shield 202 from the retracted position to the extended position may counteract or partially or completely oppose a proximally directed force on the needle shield 202. For example, in the variation shown in fig. 3A-3F, the distal end 212 of the needle shield 202 is configured to be pressed against tissue of a patient during injection. Thus, the tissue may apply a force to the distal end 212 of the needle shield 202, partially or completely counteracting the biasing force from the biasing element 218 (e.g., compression spring 220) when the injection device 100 is pressed against the tissue. This may prevent the needle shield 202 from moving from the retracted position to the extended position even when the needle shield 202 is unlocked from the retracted position. However, if the injection device 100 is then moved away from the tissue, there may no longer be a force from the tissue to counteract the biasing force from the biasing element 218, and as a result the needle shield 202 may move from the retracted position to the extended position, as shown in fig. 3E-3F.

In some variations, such as the variations of fig. 3A-3F, the locking assembly 226 may be configured such that the needle shield 202 may be unlocked from the retracted position just prior to the distal tip 424 of the needle 406 of the syringe 104 being extended from the distal end 158 of the nose 116, as shown in fig. 3C-3D. Thus, when the needle 406 is exposed such that it can pierce or otherwise contact tissue of the patient, the needle shield 202 is unlocked from the retracted position. The needle 406 being exposed for injection can therefore only be maintained by maintaining a proximal force on the distal end 212 of the needle shield 202 to hold it in the retracted position (e.g., by pressing the distal end 212 of the needle shield 202 against the tissue of the patient); once this proximal force is removed (e.g., by moving the injection device 100 away from the patient's tissue), the needle shield 202 may be moved to the extended position, which may prevent the needle 406 from penetrating the patient's tissue or contact between the needle 406 and the patient's tissue.

In some variations, the needle shield 202 of the needle safety assembly 200 may additionally or alternatively be configured to be locked in the extended position once moved to the extended position. That is, the needle shield 202 may be configured such that it cannot return to the retracted position once it enters the extended position. In some variations where the locking assembly includes one or more latches, the same latches can be used to lock the needle shield 202 in the extended position. In some of these variations, as shown in fig. 3E-3F, the syringe barrel 430 may include four distal slots 176 configured to mate with the tabs 234 of the latch 228 of the locking assembly 226. The distal slots 176 may be located on the syringe barrel 430 to coincide with the location of the tabs 234 when the needle shield 202 is in the extended position. When the needle shield 202 is moved to the extended position, the tab 234 on the latch 228 can mate with the distal slot 176. When the tabs 234 on the latch 228 mate with the distal slots 176, the locking assembly 226 may prevent movement of the needle shield 202 relative to the syringe sleeve 430, and in turn, may cause the locking assembly 226 to prevent movement of the needle shield 202 relative to the distal housing 110. Once locked in the extended position, the needle shield 202 can, for example, prevent a proximal force on the distal end 212 of the needle shield 202 (e.g., from tissue pressed against the distal end 212 of the needle shield 202) from tending to urge the needle shield 202 proximally toward the retracted position and/or the needle shield 202 can prevent a distal force applied thereto (e.g., from the biasing element 218) from tending to urge the needle shield 202 further away from the distal housing 110. In variations of injection devices configured to lock in an extended position, this feature may limit the ability of the needle to extend from the distal end of the nose to pierce or otherwise contact tissue or other surfaces after the injection device has been removed from the patient's tissue. This may make the injection device safer for the user and/or the patient by limiting accidental needle sticks after the injection has been fully or partially completed. However, it should be appreciated that in other variations, the needle shield may not be configured to lock when in the extended position (e.g., in some variations, the needle shield 202 may retract from the extended position in response to a distal force).

In some variations, the needle safety assembly 200 may provide feedback to the user. In some variations, this feedback may include a biohazard indicator, such as a biohazard symbol located on the outer surface of the needle shield 202 that is visible when the needle shield 202 is in the extended position. Additionally or alternatively, all or a portion of the needle shield 202 may be colored (e.g., red, yellow, orange, green, magenta, blue, etc.) to indicate or signal to the user that the injection device 100 has been used.

The housing 102 may include an indicator to indicate the progress or completion of an injection. In one variation, the indicator may have a range of configurations corresponding to various levels of progress of the injection. In some such variations, the configurations may have different visual, tactile, or audible perceptions, such as, but not limited to, color, numerical value, sequence cues or indicia, or the position of the proximal housing 108 relative to the distal housing 110. In the same or other variations, the transition between the unactivated configuration and the activated configuration and/or the transition between the configurations may produce a visual, tactile, or audible alert, such as, but not limited to, a color, numerical value, or sequential cue or indicia, or the position of the proximal housing 108 relative to the distal housing 110.

In some variations, the indicator may alert the user that a full dose has been displaced from the reservoir 414 of the syringe 104 and/or that the seal 410 has traveled the full length of the reservoir 414 to the distal end 462 of the syringe cavity 404 (described below). Additionally or alternatively, the dose tip indicator may alert the user that the entire dose has been displaced from the reservoir 414 of the syringe 104 and/or that the seal 410 has traveled to near (e.g., greater than or equal to about 85%, greater than or equal to about 90%, greater than or equal to about 95%, or more, or within about 1mm of full displacement, about 2mm of full displacement, about 3mm of full displacement, or about 4mm of full displacement, etc.) the full length of the reservoir 414 to the distal end 462 of the syringe cavity 404.

Fig. 4A-4C show longitudinal cross-sectional views of the proximal portion of the injection device of fig. 1, showing the dose tip indicator 300 having different appearances in relation to an inactivated configuration (fig. 4A) and an activated configuration (fig. 4C). The indicator 300 is visible through the housing 102 in the activated configuration and is not visible through the housing 102 in the inactivated configuration. In some variations, at least a portion of the housing 102 may be translucent, transparent, or include an opening to allow the appearance of the indicator 300 to differ between the activated and unactivated configurations. For example, the indicator 300 may be visible through the end cap 118 of the proximal housing 108 when in the activated configuration, and the end cap 118 may comprise a transparent or translucent material. While in the variation of fig. 4A-4C, the transparent or translucent area is in the end cap 118, it should be appreciated that in other variations, the indicator 300 may be visible through other portions of the housing 102.

In the variation shown in fig. 4A-4C, the indicator 300 may include a body 302, a release member 308, and a biasing element 320. The body 302 of the proximal housing 108 and the end cap 118 may be configured such that, when the body 302 is adjacent to the inner surface 186 of the end cap 118, at least a portion of the body 302 is visible from outside the end cap 118 through the viewing portion. In some variations, at least a portion of body 302 may have a color or pigment that can be more easily noticed, such as, but not limited to, red, yellow, orange, green, magenta, blue, and the like. To see the body 302 through at least a portion of the endcap 118, in some variations, at least a portion of the endcap 118 can be translucent. In variations where a portion of end cap 118 is translucent, the degree of translucency may be such that the coloration of body 302 is only perceptible through end cap 118 when body 302 is adjacent or near adjacent the viewing portion. In other variations, end cap 118 may include a transparent or open area configured such that, for example, due to the viewing angle, when body 302 is adjacent to the transparent or open area, body 302 is only visible through the viewing portion. For example, in some such variations, the viewing portion may include a transparent region around the circumference of the end cap 118, and the body 302 of the indicator 300 may only be visible through the viewing portion when aligned near the viewing portion. Body 302 of indicator 300 may also include a lumen 304 therethrough to allow a portion of a ram 502 (described below) to pass through body 302.

The biasing element 320 may be configured to bias the indicator 300 toward the activated configuration. The biasing element 320 may have a compressed configuration and an expanded configuration. The biasing element 320 may be in a compressed configuration when the indicator 300 is in the unactuated configuration, and the biasing element 320 may be in an expanded configuration when the indicator 300 is in the actuated configuration. As shown in fig. 4A-4C, in some variations, the biasing element 320 may include a compression spring 322. The proximal end 324 of the compression spring 322 may be connected or in contact with the body 302 of the indicator 300 and the distal end 326 of the compression spring 322 may be connected or in contact with an interlock 436 (described below). Biasing element 320 may thus bias body 302 of indicator 300 away from ram 502.

As shown in fig. 4A, the release member 308 may retain the indicator 300 in the unactuated configuration until released. The release member 308 may include an elongated portion 312 and a locking portion 310. An elongated portion 312 may connect the body 302 and the lock 310, and the lock 310 may extend radially outward from a distal end of the elongated portion 312. The radially outer end of the lock 310 may fit within the indicator recess 328 in the interlock 436 when the indicator 300 is in the inactivated configuration. Radially outward pressure on the inner end of the lock 310 from the plunger 510 may prevent the lock 310 from moving radially inward to emerge from or disengage from the recess 328. Protrusion of the outer tip of lock 310 into indicator recess 328 may cause a distally directed force on lock 310 from the proximal surface of recess 328 that may counteract the biasing force of compression spring 322, and which may thus maintain indicator 300 in the inactivated configuration.

When the release member 308 is released, the indicator 300 may no longer be held in the unactuated configuration, as shown in fig. 4B. Release member 308 may be released by distal movement of ram 502 as the injection progresses (as described in more detail below). As ram 502 moves distally relative to interlock 436, plunger 510 may move distally relative to lock 310 of release member 308 until plunger 510 may be fully distal of lock 310, as shown in fig. 4B. At this point, the plunger 510 may no longer contact the inner end of the lock 310 to prevent the lock 310 from moving radially inward to emerge from or separate from the recess 328. As a result, the lock 310 may move radially inward to emerge from or disengage from the recess 328, and the proximal surface of the recess 328 may no longer provide a distally directed force on the lock 310 to counteract the biasing force from the compression spring 322, thereby releasing the release member 308. Once released, the biasing force from the compression spring 322 may move the indicator 300 proximally relative to the interlock 436 and toward the activated configuration, as shown in fig. 4C.

Fig. 4D-4E show cut-away elevational side views of a proximal portion of another embodiment of an injection device showing another example of a dose tip indicator in an unactivated configuration (fig. 4D) and an activated configuration (fig. 4E). 4D-4E, similar to the embodiment of FIGS. 4A-4C, the indicator 300 can include a body 2302, a release member 2308 and a biasing element 2320, while a proximal end 2324 of a compression spring 2322 can be coupled to or in contact with an inner lip 2306 on the body 2302 of the indicator 2300 and a distal end 2326 of the compression spring 2322 can be coupled to or in contact with the arm 506 of the ram 2502. Release member 2308 may include one or more latches 2310 that may mate with slots or other forms of recesses in arm 2506 of ram 2502. When latch 2310 mates with the slot or recess, release member 2308 can prevent distal movement of body 2302 of indicator 2300 relative to ram 502 (e.g., due to the biasing force from biasing element 2320). If latch 2310 is released from the slot or recess, the force from biasing element 2320 may move indicator 2300 into the activated configuration, as shown in FIG. 4E. In the embodiment shown in fig. 4D-4E, for example, the release member 2308 can include two latches 2310. Each latch 2310 can extend distally from a body 2302 of indicator 2300. Each latch 2310 can be configured to mate with a retracting ridge 2524 on the outer surface of the arm 2506 of the striker 2502. When the latch 2310 mates with the retraction ridge 2524, the proximal side of the retraction ridge can prevent the latch 2310, and thus the body 2302 of the indicator 2300, from moving proximally due to the biasing force from the compression spring 2322. However, if latch 2310 is released from retracting ridge 2524, the biasing force from compression spring 2322 may urge striker 2502 and indicator 2300 apart, moving body 2302 of indicator 2300 toward end cap 2118 of proximal housing 2108, which may make indicator 2300 visible through end cap 2118. Tab 2103 can be configured to be released from retraction ridge 2524 by distal movement of ram 2502 relative to proximal housing 2108 and end cap 2118. When ram 2502 has moved distally such that the full dose has been displaced from the reservoir of the syringe and/or nearly the full dose has been displaced from the reservoir of the syringe, latch 2310 can be pushed out of retraction ridge 2524, moving indicator 2300 to the activated configuration, as shown in fig. 4E.

While the indicator in fig. 4A-4E is a dose tip indicator, in other variations, the indicator may be configured to communicate the progress of one or more points throughout the injection process. For example, in some variations, the proximal housing 108 and/or the distal housing 110 may include a viewing area (e.g., a transparent or translucent area, or an opening) such that the position of the interlock 436 (described below) is viewable through the viewing area. The position of the interlock 436 relative to the housing 102 may indicate the progress of the injection. In some of these variations, the interlock 436 may be colored or may include a colored region to be more easily visible through the viewing region. In other variations, a separate member, which may also be colored or include a colored region, may be attached to the interlock 436, which is visible through the viewing region.

As briefly mentioned above, generally, the injector 104 may include: an injector body defining an injector cavity; a seal slidably disposed within the lumen of the syringe cavity, the seal defining a reservoir that can hold a formulation comprising a therapeutic or diagnostic agent; a ram including a plunger slidably engaged within the syringe cavity; and a needle at the distal end of the syringe body. The needle may be configured to pierce tissue of a patient receiving an injection and may have a lumen through which the contents of the reservoir are delivered to the tissue of the patient. Distal movement of the seal within the syringe cavity displaces the contents of the reservoir through the lumen of the needle.

Referring to fig. 2A-2N, the injector 104, as briefly described above, may include an injector body 402 that may define an injector cavity 404. The syringe cavity 404 may be in fluid communication with a lumen 408 of a needle 406 described in more detail below. The seal 410 may be slidably disposed within the syringe cavity 104 and may form an airtight seal with an inner surface 412 of the syringe body 402. The inner surface 412 of the syringe body 402 and the seal 410 may form a reservoir 414 configured to hold a formulation, such as a solution, containing a therapeutic or diagnostic agent. The seal 410 may restrict the flow or otherwise move the contents of the syringe chamber 404 to the proximal side of the seal 410. The volume of the reservoir 414 can be reduced if the seal 410 is moved distally relative to and within the syringe cavity 404. Thus, distal movement of the seal 410 relative to and within the syringe cavity 404 may displace the contents of the reservoir 414 through the lumen 408 of the needle 406. In some variations, reservoir 414 may be configured to contain a maximum volume of about 1mL, about 2mL, about 3mL, about 4mL, or about 5 mL. In other variations, reservoir 414 may be configured to contain a maximum volume of about 0.1mL to 1mL, 1mL to 2mL, 2mL to 3mL, 3mL to 5mL, 5mL to 10mL, 10mL to 15mL, 15mL to 20mL, 20mL to 25mL, or more. Although the syringe 104 is shown as having a circular cross-section and thus the syringe body 402 forms a barrel, in other variations, the syringe 104 and its components may have any suitable shape (e.g., having an elliptical cross-section, an oblong cross-section, an oval cross-section, a square cross-section, a rectangular cross-section, a triangular cross-section, etc.).

The reservoir 414 formed by the inner surface 412 of the syringe body 402 and the seal 410 may contain a formulation containing one or more therapeutic or diagnostic agents. In some variations, the therapeutic or diagnostic agent may be a substance such as, but not limited to, a macromolecule, a small molecule, or a organism. In some variations, the formulation may further comprise one or more solvents, diluents, and/or adjuvants. The formulation may have any suitable viscosity. Generally, the formulation may have a viscosity of up to 10cP, up to 20cP, up to 30cP, up to 40cP, up to 50cP, up to 60cP, up to 70cP, up to 80cP, up to 90cP, or up to 100 cP. In some cases, the formulation may have a higher viscosity, for example, up to 1,000cP, up to 10,000cP, or up to 50,000 cP. Examples of higher viscosity injections include certain dermal fillers for cosmetic or tissue bulking procedures such as the treatment of urinary incontinence. In some cases, the formulation may have a significantly higher viscosity (e.g., a much higher viscosity, such as up to 500,000cP or higher).

In some variations, the therapeutic or diagnostic agent may be a substance that is useful for a patient population who may benefit from a power-assisted injection device as described herein, such as a patient population suffering from a disease or disorder such as, but not limited to, multiple sclerosis, rheumatoid arthritis, cancer, alzheimer's disease, or IgE-mediated disorders (e.g., allergic rhinitis, asthma (e.g., allergic asthma or non-allergic asthma), atopic dermatitis, allergic gastrointestinal disease, allergic reactions (e.g., allergy, urticaria, food allergies, etc.), allergic bronchopulmonary aspergillosis, parasitic diseases, interstitial cystitis, hyper IgE syndrome, telangiectasia, wiskott-aldrich syndrome, thymic lymphoid dysplasia, IgE myeloma, and graft-versus-host reaction). In some variations, the therapeutic or diagnostic agent may be, but need not be, selected from interferon-beta (e.g.,

) Natalizumab

TNF alpha inhibitors (e.g., fusion proteins)

Infliximab

Adalimumab

Gaolilizumab

And tuzumab

) Brazipu, Albapula

Anakinra

anti-CD 20 antibodies (e.g., rituximab)

Or ocrelizumab), anti-IL-6 receptor antibodies (e.g., tacrine monoclonal antibody)

) An anti-IL-13 antibody (e.g., rochlumab), an anti-CD 20 framework (e.g., obinutuzumab), an anti-HER 2 antibody (e.g., trastuzumab), or an anti-beta antibody (e.g., crenizumab).

In some variations, the formula may be packagedComprising a therapeutically effective amount of one or more proteins such as, but not limited to: growth hormones, including human growth hormone and bovine growth hormone, growth hormone releasing factor; parathyroid hormone; thyroid stimulating hormone; a lipoprotein; alpha-1-antitrypsin; insulin a-chain; insulin B-chain; proinsulin; follicle stimulating hormone; a calcitonin; luteinizing hormone; glucagon; blood coagulation factors such as factor VIIIC, factor IX, tissue factor and von willebrand factor; anti-coagulation factors such as protein C; atrial natriuretic peptides; a pulmonary surfactant; a plasminogen activator, such as urokinase or a tissue-type plasminogen activator (t-PA, e.g.,

) (ii) a bomazine; thrombin; tumor necrosis factor-alpha and-beta; enkephalinase; RANTES (activated to regulate normal T cell expression and secretion of the factors "regulated on activation normal T-cell expressed and secreted"); human macrophage inflammatory protein (MIP-1-beta 0); serum albumin such as human serum albumin; (ii) a muller inhibitor; a relaxin a-chain; a relaxin B-chain; prorelaxin; mouse gonadotropin-related peptides; DNase; a statin; an activin; vascular Endothelial Growth Factor (VEGF); receptors for hormones or growth factors; an integrin; protein A or D; rheumatoid factor; neurotrophic factors such as osteoprogenitor neurotrophic factor (BDNF), neurotrophin-3, -4, -5 or-6 (NT-3, NT-4, NT-5 or NT-6) or nerve growth factors such as NGF-P; thrombogenic growth factor (PDGF); fibroblast growth factor such as aFGF or bFGF; epidermal Growth Factor (EGF); transforming Growth Factors (TGF) such as TGF-alpha and TGF-beta, including TGF-beta 1, TGF-beta 2, TGF-beta 3, TGF-beta 4 or TGF-beta 5; insulin-like growth factors-I and-II (IGF-I and IGF-II); des (1-3) -IGF-I (brain IGF-I); insulin-like growth factor binding proteins; CD proteins such as CD3, CD4, CD8, CD19, and CD 20; erythropoietin (EPO); thrombopoietin (TPO); an osteoinductive factor; an immunotoxin; bone Morphogenetic Protein (BMP); interferons such as interferon-alpha -beta and-gamma; colony Stimulating Factors (CSF), such as M-CSF, GM-CSF, and G-CSF; interleukins (IL), such as IL-1 through IL-10; superoxide dismutase; a T cell receptor; a surface membrane protein; decay Acceleration Factor (DAF); viral antigens such as part of the AIDS virus mask; a homing receptor; an address element; a regulatory protein; an immunoadhesin; an antibody; and biologically active fragments or variants of any of the above-listed polypeptides. "protein" refers to an amino acid sequence of sufficient chain length to produce higher levels of tertiary and/or quaternary structure. In some of these variations, the formulated protein may be substantially pure and substantially homogeneous (i.e., free of contaminating protein). "substantially pure" protein refers to a complex comprising at least about 90% by weight, preferably at least about 95% by weight, of protein, based on the total weight of the complex. By "substantially homogeneous" protein is meant a complex comprising at least about 99% by weight protein, based on the total weight of the complex.

In some variations, the formulation may comprise a high concentration of large molecular weight proteins, such as antibodies or immunoglobulins. For example, the antibody may be an antibody directed against a particular predetermined antigen. In a particular aspect, the antigen is IgE (e.g., rhuMAbE-25, rhuMAbE-26 described in U.S. Pat. No. 6,329,509 and WO 99/01556). Alternatively, the anti-IgE antibody may be CGP-5101(Hu-901) described in Corne et al, J.Clin.Invest.99(5):879-887(1997), WO92/17207, and ATTC Deposit Nos.BRL-10706 and 11130, 11131, 11132, 11133. Alternatively, antigens may include: CD proteins CD3, CD4, CD8, CD19, CD20, CD34, and CD 40; a member of the HER receptor family, such as the EGF receptor, HER2, HER3 or HER4 receptor; 2C4, 4D5, PSCA, LDP-2, cell adhesion molecules such as LFA-1, Mac1, p150, 95, VLA-4, ICAM-1, VCAM, and α v/β 3 integrins, including the α -and β -subunits thereof (e.g., anti-CD 11a, anti-CD 18, or anti-CD 11b antibodies); growth factors such as VEGF; blood group antigens; flk2/flt3 receptor; obesity (PB) receptors; mpl receptor, CTLA-4 and protein C. The antibody may also be an antibody that specifically binds to a target antigen disclosed in the following patent applications: U.S. serial No. 10/177,488 filed on 6/19/2002; U.S. serial No. 09/888,257 filed on day 22/6/2001; U.S. serial No. 09/929,769 filed on 8/14/2001; U.S. serial No. 09/938,418 filed on 8/23 of 2001; U.S. serial No. 10/241,220 filed on 9/11 2002; U.S. serial No. 10/331,496 filed on 30/12/2002; U.S. serial No. 10/125,166 filed on 17.4.2002; U.S. serial No. 10/127,966 filed on 23/4/2002; U.S. serial No. 10/272,051 filed on day 10, 16, 2002; U.S. serial No. 60/299,500 filed on day 6, month 20, 2001; U.S. serial No. 60/300,880 filed on 25/6/2001; U.S. serial No. 60/301,880 filed on 29/6/2001; U.S. serial No. 60/304,813 filed on 7/11/2001; U.S. serial No. 60/312,312 filed on 8/13/2001; U.S. serial No. 60/314,280 filed on 8/22/2001; U.S. serial No. 60/323,268 filed on 9/18 of 2001; U.S. serial No. 60/339,227 filed on day 10, 19, 2001; U.S. serial No. 60/336,827 filed on 11/7/2001; U.S. serial No. 60/331,906 filed on 11/20/2001; U.S. serial No. 60/354,444 filed on day 1,2, 2002; U.S. serial No. 60/351,885 filed on 25/1/2002; U.S. serial No. 60/360,066 filed on 25/2/2002; U.S. serial No. 60/362,004 filed on 3/5/2002; U.S. serial No. 60/366,869 filed on 3/20/2002; U.S. serial No. 60/366,284 filed on 3/21 2002; U.S. serial No. 60/368,679 filed on 3/28/2002; U.S. serial No. 60/369,724 filed on 3.4.2002; U.S. serial No. 60/373,160 filed on day 4, 16, 2002; U.S. serial No. 60/378,885 filed on 5/8 2002; U.S. serial No. 60/404,809 filed on 8/19/2002; U.S. serial No. 60/405,645 filed on day 821 of 2002; U.S. serial No. 60/407,087 filed on 8/29 2002; U.S. serial No. 60/413,192 filed on 9/23 2002; U.S. serial No. 60/419,008 filed on day 10, 15, 2002; U.S. serial No. 60/426,847 filed on 11/15/2001; U.S. serial No. 60/431,250 filed on 6.12.2002; U.S. serial No. 60/437,344 filed on 31/12/2002; U.S. serial No. 60/414,971 filed on day 10, 2, 2002; U.S. serial No. 60/418,988 filed on month 10, 18, 2002 and roll No. PR5035 filed on month 2, 5, 2003. The term "antibody" as used herein can include monoclonal antibodies (including full length antibodies with immunoglobulin Fc regions), antibody complexes with polypeptide specificity, multispecific antibodies (e.g., bispecific antibodies, diabodies, and single chain molecules, and antibody fragments (e.g., Fab, F (ab') 2, and Fv).

In some variations, the therapeutic agent may be a subcutaneous formulation comprising a high concentration of large molecular weight proteins such as immunoglobulins. For example, the immunoglobulin may be an antibody directed against a particular predetermined antigen, which may include, for example: IgE (e.g., rhuMAbE-25, rhuMAbE-26, and rhuMAbE-27 described in WO 99/01556); CD proteins such as CD3, CD4, CD8, CD19, CD20, CD34, and CD 83; a member of the HER receptor family, such as the EGF receptor, HER2, HER3 or HER4 receptor; cell adhesion molecules such as LFA-1, Mol, p150,95, VLA-4, ICAM-1, VCAM, and α v/β 3 integrin, including the α -and β -subunits thereof (e.g., anti-CD 11a, anti-CD 18, or anti-CD 11b antibodies) or integrin β 7; growth factors such as VEGF; blood group antigens; flk2/flt3 receptor; obesity (OB) receptors; interleukins, such as IL2, IL3, IL4, IL5, IL6 and IL6 receptors, IL13, IL17, IL21, IL22, IL23, IL24, IL26, IL27, IL30, IL32, IL 34; beta-amyloid protein; interferons such as interferons I and II, which may include interferon alpha: IFNA1, IFNA2, IFNA4, IFNA5, IFNA6, IFNA7, IFNA8, IFNA10, IFNA13, IFNA14, IFNA16, IFNA17, IFNA21 and interferon beta: IFN- β 1 and IFN- β 3; anaphylatoxins or complement activators such as C2, C2a, C5, C5 a; and protein C.

Although formulations containing one or more therapeutic or diagnostic agents are described above with respect to the injector 104 of the injection device 100, it should be understood that the formulations described above may be injected using any of the variations of the injection devices described herein, including the injection devices 700 and 1300 described below.

The syringe 402 and seal 410 and/or injection may comprise any suitable material, such as, but not limited to, glass (e.g., type 1 glass), polymer (e.g., rubber, such as butyl rubber), metal, and the like. In some variations, the material of the syringe body 402 and/or the seal 410 may have properties that do not substantially interact with the therapeutic or diagnostic agent, resist adhesion, and/or promote adhesionStability and/or sterility or sterilizability of the formulation. In some variations, the syringe body may include a coating. In some variations, the coating may comprise silicone oil, fluoropolymer (e.g., perfluoropolyether-based chemical coating, polytetrafluoroethylene)

) And the like. For example, the syringe body may comprise glass which may be siliconized on the inside. In some variations, the syringe body 402 and/or the seal 410 may comprise a material that limits light transmission to the therapeutic or diagnostic agent (i.e., a material that reflects or absorbs light), such as, but not limited to, a material that blocks ultraviolet light and/or light having a particular visible wavelength (e.g., an amber material), a material that blocks all light, and a foil liner. The materials may be selected for their specific color, resistance to discoloration (due to aging, exposure to the formulation, or due to sterilization), resistance to leaching with respect to certain common or specific formulation characteristics. In some variations, the syringe body 402 may comprise a translucent or transparent material such that the contents of the syringe body 402 may be viewed through the material. In some variations, the shelf life of the therapeutic or diagnostic agent within the injection device 100 may be up to about 1 year, about 2 years, about 3 years, about 4 years, or about 5 years.

The needle 406 of the syringe 104 may be attached to the distal end of the syringe body 402 of the syringe 104. The proximal end 416 of the needle 406 may be secured to the distal end 418 of the syringe body 402 such that the proximal end 416 of the lumen 408 of the needle 406 is in fluid communication with the distal opening 420 at the distal end 418 of the syringe body 402. The distal end 418 of the needle 406 may have a pointed shape configured to pierce tissue. The needle 406 thus may be configured to allow the formulation within the reservoir 414 to flow out through the distal opening 420 in the syringe body 402, through the lumen 408 of the needle 406, and into tissue as the needle 406 is inserted into the tissue. The length and gauge of the needle 406 may be adapted for the intended use. For example, in some variations, the syringe 104 may include needle sizes up to or including, but not limited to, 7ga, 9ga, 11ga, 13ga, 15ga, 17ga, 19ga, 21ga, 23ga, 25ga, 27ga, 29ga, 31ga, and 33ga needles and lengths up to about 3mm, 4mm, 6mm, 8mm, 10mm, 15mm, 20mm, 30mm, 40mm, or more. The needle may comprise any suitable material including, but not limited to, stainless steel. In other variations, the device may not be provided with a needle. In some variations, the needle-free device is designed to attach to an existing needle (e.g., a lumbar puncture needle or a midline catheter).

As shown in fig. 1, the syringe 104 may also include a rigid needle shield 422. In some variations, the injection device 100 may include a deshielder configured to allow easy removal of the rigid needle shield 422. In some variations, the unsheather or rigid needle shield 422 may include an interlock to prevent movement of the syringe 104 within the distal housing 110 prior to removal of the rigid needle shield 422. In some variations, the sheath remover may be integral with the cap 148, and the cap 148 may be fitted over the distal housing 110 as described in more detail above. In some variations, the rigid needle shield 422 may be asymmetric to prevent rolling of the housing 102 when attached to the injection device 100.

The syringe 104 may be configured to move longitudinally relative to the distal housing 110 from a retracted position (shown in fig. 2A-2D and 3A-3B) to an extended position (shown in fig. 2G-2N and 3E-3F). In the retracted position, the distal tip 424 of the needle 406 may be shielded from exposure (e.g., the needle 406 may be protected from piercing or otherwise contacting tissue), and thus the distal tip 424 of the needle 406 may be located proximal to the distal end of the housing 102 (e.g., the distal end 114 of the distal housing 110). The syringe 104 may be held in a retracted position by the restraining element (e.g., it may resist distal movement relative to the syringe 104). In some variations, the restraining element may include one or more of the bends 428 described below. The syringe 104 may be moved toward the extended position by a distal force sufficient to overcome the resistance of the bend 428 as described below. In the extended position, the distal tip 424 of the needle 406 may be exposed (e.g., the distal tip 424 of the needle 406 may be able to pierce or otherwise contact tissue), and thus the distal tip 424 of the needle 406 may be located distal to the distal end of the housing 102 (e.g., the distal end 114 of the distal housing 110). When the syringe 104 is in the extended position, if the needle shield 202 of the needle safety assembly 200 is in the retracted position, the distal tip 424 of the needle 406 may extend beyond the distal end of the distal housing 110 and the needle shield 202 to penetrate tissue to a desired depth, as shown in fig. 2G-2L. In some variations, the distal tip 424 of the needle 406 may move between the retracted position and the extended position by about 6mm to 8mm, about 8mm to 10mm, about 10mm to 12mm, or about 12mm to 14 mm. In some variations, the distal tip 424 of the needle 406 may be about 1mm, about 2mm, about 3mm, about 4mm, about 5mm, about 6mm, or about 7mm proximal to the distal end 114 of the distal housing 110 in the retracted position. In some variations, the distal tip 424 of the needle 406 may be about 4mm, about 5mm, about 6mm, about 7mm, about 8mm, about 9mm, or about 10mm distal to the distal end 114 of the distal housing 110 in the extended position.

Fig. 5 shows an exploded perspective view of the injection device 100. In some variations, the injection device 100 may include the syringe sleeve 430 as described above, but need not be. In these variations, syringe 104 may be slidably disposed within syringe barrel 430. Syringe sleeve 430 may include a distal portion 432 and a proximal portion 434. Distal portion 432 may be configured to slidably fit around syringe body 402. Proximal portion 434 may have a larger diameter (or maximum distance transverse to the longitudinal axis) than distal portion 432 and may be configured to hold force assembly 106 in place, as described in more detail below. Syringe sleeve 430 may be fixed relative to distal housing 110 and may have a longitudinal axis that coincides with the longitudinal axis of housing 102. The syringe barrel may comprise any suitable material, and in some variations, the syringe barrel 430 may comprise deep drawn metal.

The distal portion 432 of the syringe barrel 430 may also have an interlock 436 attached thereto. As shown in fig. 6A-6B, the interlock 436 may include a body 438 that may be secured within the proximal portion 434 of the syringe barrel 430. The interlock 436 may have a proximal opening 440, a distal opening 442, and a lumen 444 therethrough. At least a portion of the ram 502 (described below) may fit through the proximal opening 440 of the interlock device 436 and the syringe body 402 of the syringe 104 may fit through the distal opening 442 of the interlock device 436. The interlock 436 may also include one or more bends 428 to prevent distal movement of the syringe 104, and a clutch interlock 448 to hold the clutch 608 of the force module 106 in place, both of which are described in greater detail below.

Returning to fig. 2A-2N, ram 502 may be directly or indirectly connected to proximal housing 108 such that movement of proximal housing 108 may be transferred to ram 502. Ram 502 may be configured to transfer the distal force on proximal housing 108 into different motions depending on the stage of the injection process. In the first stage, distal forces on the proximal housing 108 may be transferred into distal movement of the syringe 104 relative to the distal housing 110. In the second stage, the distal force on the proximal housing 108 may be transferred into displacement of the contents of the reservoir 414 of the syringe 104 (e.g., a fluid or formulation containing a therapeutic or diagnostic agent) through the lumen 408 of the needle 406.

In some variations, ram 502 may be configured such that the application of distal force on proximal housing 108 may occur in the order described above. That is, the ram 502 may be configured such that the distal force on the proximal housing 108 may be transferred first into the distal movement of the syringe 104 relative to the distal housing 108, and then second into the displacement of the contents of the reservoir 414 (e.g., the formulation containing the therapeutic agent) through the lumen 408 of the needle 406. This may be desirable, for example, because it may allow the syringe 104 to be moved distally so that the needle 406 may pierce the patient's tissue before the contents of the reservoir 414 are displaced through the lumen 408 of the needle 406.

In some variations, the sequence of application of the distal force on the proximal housing 108 may be attributable to different amounts of force required for each movement. For example, when the force on the proximal housing 108 is above a first threshold (e.g., above about 1N, above about 2N, above about 3N, above about 4N, above about 5N, above about 6N, above about 7N, or higher), the ram 502 may transfer a distal force on the proximal housing 108 into the distal motion of the syringe 104 relative to the distal housing 110; and when the force on proximal housing 108 is above a second higher threshold (e.g., above about 1N, above about 2N, above about 4N, above about 6N, above about 8N, above about 10N, above about 12N, above about 14N, or higher), ram 502 may transfer the distal force on proximal housing 108 into displacement of the contents of reservoir 414 through needle 406. In some cases, these thresholds may be desirable for other or additional reasons. For example, it may be desirable for the force threshold to initiate distal movement of the injector to be higher than the amount of force required to insert the needle through the skin. It may also be desirable for the force threshold to initiate distal movement of the syringe to be high enough to prevent unintended distal movement. Indeed, in some variations, it may be desirable for the force threshold to initiate distal movement of the syringe to be high enough to force rapid needle insertion. In some variations, each threshold may be attributed to a proximal force on the syringe 104 and ram 502, respectively, from friction. In other variations, each threshold may be attributed to proximal forces on the syringe 104 and ram 502, respectively, from other sources, such as proximal forces from a kink or spring. In other variations, one or more of the thresholds may be due to proximal forces on the syringe 104 and ram 502, respectively, from friction and other sources. It should be appreciated that in other variations, ram 502 may transmit the distal force on proximal housing 108 into different motions in different orders and through different mechanisms. For example, in some variations, the application of the distal force may be selected by a mechanism for manual selection by a user. It should also be appreciated that the ram may transfer the distal force on the proximal housing 108 into more or less motion.

As shown in fig. 2A-2N, the ram 502 may include a central portion 502 and two arms 506 extending from opposite sides of the central portion 502. The central portion 504 may be divided into a proximal central portion including a connecting rod 508 and a distal central portion including a plunger 510. Two arms 506 may extend from the central portion 504 at a separation point 512 between the plunger 510 and the connecting rod 508. The connecting rod 508 is slidable within a portion of an actuation rod 636 (described in detail below), which actuation rod 636 in turn may be fixedly attached to the end cap 118 of the proximal housing. However, in other variations (not shown), the connecting rod may be configured to directly connect the ram with the proximal housing. In these variations, the connecting rod may at least partially fit into a receiving recess on an inner surface of the end cap of the proximal housing. The receiving pocket may be located in the center of the end cap and may be configured to hold the ram in a position aligned with the longitudinal axis of the housing.

The plunger 510 may be configured to slide within the syringe cavity 404 of the syringe 104. The distal end 516 of the plunger 510 may be configured to engage the seal 410 of the syringe 104. If the plunger 510 is moved distally relative to and within the syringe chamber 404, the plunger 510 may push the seal 410 distally relative to and within the syringe chamber 404. This movement of the seal 410 may reduce the volume of the reservoir 414 containing the formulation containing the therapeutic or diagnostic agent. Thus, distal movement of the plunger 510 and, thus, the seal 410 relative to and within the syringe cavity 404 may displace the contents of the reservoir 414 through the lumen 408 of the needle 406. The two arms 506 of ram 502 can extend distally along central portion 504 from opposite sides of ram 502 about its split point 512. The arm 506 may include a proximal curved portion 518 and a distal straight portion 520. The straight portions 520 of the arms 506 may be radially spaced from the plunger 510 such that if the plunger 510 is moved within the syringe cavity 404, the straight portions 520 of the arms 506 may be located outside of the syringe body 402. In some variations, the outer surface of the straight portion of the arm 506 may optionally include a retracting ridge for attaching an indicator as described above. The arm 506 may be further configured to attach to a portion of the power assembly 106 when the syringe 104 is in the extended position, as described below.

As shown in fig. 2E-2F, at a first stage of the injection procedure, if distal housing 110 is held in place (e.g., by pressing distal end 158 of nose 116 of distal housing 110 against the patient's tissue) and the distal force is above the necessary force threshold, the distal force on proximal housing 108 may be transferred into distal movement of syringe 104 relative to syringe sleeve 430 from a retracted position (shown in fig. 2C-2D) to an extended position (shown in fig. 2G-2H). The required threshold force may be attributed to the first pair of bent portions 428 as described above. More specifically, when the desired threshold force is reached, the bent portion 428 may bend outward and over the proximal lip 452 of the syringe body 402, at which point the bent portion 428 may no longer prevent distal movement of the syringe 104. A distal force on proximal housing 108 may then cause distal movement of ram 502, which in turn may cause distal movement of syringe 104 toward the extended position via plunger 510 located within syringe cavity 404. The syringe 104 may be moved distally within the syringe barrel 430, which may cause the needle 406 of the syringe 104 to move distally toward the distal end of the nose 116 of the distal housing 110. As the distal tip 424 of the needle 406 approaches the distal end 158 of the nose 116 (shown in fig. 2E-2F), the needle shield 202 of the needle safety assembly 200 may be unlocked from the retracted position, as described in detail above. As the distal tip 424 of the needle 406 moves to protrude beyond the distal end 158 of the nose 116, the needle 406 may pierce tissue pressed against the distal end 158 of the nose 116. The syringe 104 may continue to move distally relative to the syringe barrel 430 until the syringe 104 has reached the extended position (shown in fig. 2G-2H). In the extended position, the distal tip 424 of the needle 406 may have reached the desired depth as described above. Forward movement of the syringe 104 beyond the extended position may be limited by the proximal lip 452 contacting the distal end of the proximal portion 434 of the syringe barrel 430. Since the proximal portion 434 of the syringe sleeve 430 may have a larger diameter (or maximum distance transverse to the longitudinal axis) than the distal portion 432 as described above, the proximal lip 452 of the syringe body 402 may fit within the proximal portion 434, but may not fit within the distal portion 432. In some variations, the injection device 100 may include a dampening element (e.g., a rubber or elastomer or other rubber or elastomer element overmolded on the interlock 436) with which the proximal lip 452 may contact when reaching its fully proximal position.

It should be noted that due to the relative amounts of force required to move syringe 104 relative to syringe sleeve 430 and to move ram 502 relative to syringe 104 as described above, and due to the mechanism that can resist distal movement of ram 502 relative to syringe 104, syringe 104 can move distally with ram 502 rather than ram 502 moving distally relative to syringe 104 in response to application of a distal force on proximal housing 108 (e.g., due to plunger 510 moving distally relative to syringe cavity 404 and within syringe cavity 404). More specifically, the amount of force required to overcome the first set of bends 428 that can hold the syringe 104 in place relative to the interlock 436 as described above can be less than the amount of force to overcome the rate control assembly 604 of the force assembly 106 (described below) and/or the lock of the indicator that prevents distal movement of the plunger 510 within the syringe cavity 404 of the syringe 104, as described in more detail below. If the distal force on the proximal housing 108 is released while the syringe 104 is moved from the retracted position to the extended position, the syringe 104 may remain in place relative to the syringe barrel 430.

In the variation shown in fig. 2A-2N, distal movement of the plunger 510 within the syringe cavity 404 may be prevented until the syringe 104 is in the extended configuration due to the locking portion of the indicator 300 described above. Before the syringe 104 is in the extended position, the protrusion 316 on the inner edge of the locking portion 410 may mate with the recess 330 in the plunger 510, as shown in fig. 2A, 2C, and 2E. Inward pressure on the outer end of the lock 310 from the inner surface of the interlock 436 may prevent the lock 310 from moving radially outward from the recess 330, thereby keeping the lock 310 and the plunger 510 mated. While mated, the indicator 300, plunger 502, and syringe 104 may be fixed relative to one another and may move distally together as the syringe 104 moves toward the extended configuration. Once the syringe 104 is in the extended configuration, as shown in fig. 2G, the lock 310 may be aligned with an indicator recess 328 (described in more detail above). When a distal force is applied to plunger 510 via proximal housing 108, pressure on the inner edge of lock 310 from plunger 510 may push lock 310 radially outward into indicator recess 328. The lock 310 and plunger 510 may thus no longer mate, allowing the plunger 510 to move distally.

After the syringe 104 has been moved distally relative to the syringe sleeve 430 such that the syringe 104 is in the extended position and the distal tip 424 of the needle 406 is at the desired depth, if the additional distal force on the proximal housing 108 is above the necessary force threshold, the force may be transferred into the distal motion of the ram 502 relative to the syringe cavity 404. When the force is above the necessary force threshold, the plunger 510 and seal 410 may move distally within the syringe cavity 404, as shown in fig. 2I-2J, which may reduce the volume of the reservoir 414 and displace the contents of the reservoir 414 through the lumen 408 of the needle 406, as described above. The distal force on the proximal housing 108 may continue to displace the contents of the reservoir 414 through the lumen 408 of the needle 406 until the seal 410 has traveled to the distal end 462 of the syringe cavity 404 (shown in fig. 2K-2L), at which point a full dose of the therapeutic or diagnostic agent may have been injected into the patient. In some variations, the total displacement of plunger 510 during distal movement of ram 502 relative to syringe cavity 404 may be about 20mm to 25mm, about 25mm to 30mm, about 30mm to 35mm, about 35mm to 40mm, about 40mm to 45mm, about 45mm to 50mm, about 50mm to 55mm, about 55mm to 60mm, about 60mm to 65mm, about 65mm to 70mm, or about 70mm to 75 mm. In some variations, once the lock 310 and plunger 510 are no longer mated, the threshold force required to move the plunger 510 and seal 410 distally within the syringe cavity 404 can be attributed to the rate control assembly 604 of the force assembly 106, as described below.

The force application assembly may include a stored energy source and a rate control assembly. The stored energy source may be configured to provide a force to displace contents of a reservoir of the injector. In some variations, the stored energy source may be configured to do so by causing the plunger or seal to move distally within the syringe cavity. In some variations, the power assembly may allow the user (patient or another person) to guide the injection process in an intuitive manner by guiding the injection by pressing the injection device against the patient's skin, but the power assembly may supply additional supplemental injection force so that the user does not have to provide all of the force required to perform the injection. Further, in some variations, the force amplifier assembly may assist in providing a desired user experience. This may include smooth operation, especially when transitioning between static, slow and fast injection states. While the force assembly in the injection device 100 provides an injection force that supplements the injection force applied by the user, it should be appreciated that in other embodiments, the force assembly may provide the entire injection force. It should also be appreciated that in some variations, the injection device may not provide supplemental injection force.

The injection force provided by the force amplifier assembly may thus be sufficient (alone or in addition to the injection force supplied by the user) to inject a particular volume of a particular formulation through a particular sized needle at a particular time. In some variations, for example, the force assembly may inject 2mL of a 19cP solution over a 17mm long 27ga thin-walled needle in 10 seconds. In some variations, the force assembly can provide a supplemental injection force of up to about 5N, about 10N, about 15N, about 20N, about 25N, about 30N, about 35N, about 40N, about 45N, about 50N, about 55N, about 60N, about 65N, about 70N, about 75N, about 80N, about 85N, or about 90N at the beginning of the injection.

In some variations, it may be desirable for the force assembly to deliver a substantially constant force during the injection process. In some variations, for example, a long spring with a low spring rate may be used to achieve a substantially constant force during injection. In some of these variations, the spring fade (fade) during injection may be about 5-10%, about 10-15%, about 15-20%, about 20-25%, about 25-30%, about 30-35%, or about 35-40%. In other variations, a substantially constant force during injection may be achieved using a spring having a shorter overall length, for example, by mounting an extension spring on a compression spring (as described in more detail with respect to the embodiment of the injection device shown in fig. 10). In other embodiments, for example, a substantially constant force during injection may be achieved using pressure from the liquid propellant at supercritical conditions (as described in more detail with respect to the embodiment of the injection device shown in fig. 18). In other variations, the force assembly may provide a force that varies during the injection process.

In some variations, the rate control assembly may include a brake assembly that may limit or inhibit displacement of the contents of the reservoir of the syringe by the stored energy source. In some variations, the rate control assembly may be configured to accomplish this by limiting or inhibiting distal movement of the plunger or seal within the syringe cavity.

Fig. 7 shows a perspective view of one example of a stored energy source 602 of the injection device 100. The stored energy source 602 may include a compression spring 606. Compression spring 606 may be directly or indirectly attached to or in contact with a first surface fixed relative to distal housing 110 at one end, and directly or indirectly attached to or in contact with a second surface fixed relative to plunger 510 of ram 502 at the other end. Thus, the force on the first and second surfaces from the compression spring 606 may bias the first and second surfaces away from each other, which in turn may bias the plunger 601 distally relative to the syringe cavity 404. More specifically, compression spring 606 may be sized to fit within distal housing 110 and around proximal portion 434 of syringe barrel 430. Compression spring 606 may be, but need not be, received by spring sleeve 610. In variations having spring sleeve 610, spring sleeve 610 may be generally cylindrical and configured to fit around compression spring 606. The spring sleeve 610 is movable relative to the syringe sleeve 430 and may have an inwardly extending distal lip 612. A distal end 616 of compression spring 606 may be attached to or connected to distal lip 612. The proximal end 614 of the compression spring 606 may be attached to or connected to an inwardly extending proximal lip 454 on the proximal portion 432 of the syringe barrel 430. the syringe barrel 430 may be fixed relative to the distal housing 110, as described above.

The force from compression spring 606 against distal lip 612 of spring sleeve 610 may be transferred into the distal motion of ram 502 by clutch 608 as shown in fig. 8A-8B. Alternatively, in some variations without a syringe barrel, the compression spring may press directly against the occluder. As shown in fig. 8A-8B, the occluder 608 can comprise a body 618. Body 618 may be configured to fit within distal housing 110 and may have an internal cavity 626 therethrough. The occluder 608 may include one or more internal protrusions 628 that extend inwardly into the lumen 626, described in more detail below. In some variations, the occluder 608 may include two attachment ports 622, and the attachment ports 622 may be configured to engage the distal ends 538 of the straight portions 520 of the arms 506 of the ram 502 when the syringe 104 reaches the extended position, as shown in fig. 2H. In some variations, distal end 538 of ram 502 may engage attachment port 622 by contacting attachment port 622 as distal end 538 moves distally of ram 502 and then snapping into place over attachment port 622. The engagement between attachment port 622 and distal end 538 is such that clutch 608 is rotatable relative to ram 502 as described in more detail below.

As shown in fig. 7, the lumen 626 of the occluder 608 may be configured to slidably fit around the distal portion 432 of the syringe sleeve 430. Although the lumen 626 is shown as having a generally circular cross-section, it should be appreciated that the lumen 626 may have any suitable shape (e.g., having an elliptical cross-section, an oblong cross-section, an oval cross-section, a square cross-section, a rectangular cross-section, a triangular cross-section, etc.), depending in part on the cross-section of the syringe 104 and/or the syringe barrel 430. As shown in fig. 7, a distal lip 612 of the spring sleeve 610 may press distally against a proximal protrusion 620 of the occluder 608. The compression spring 606 may thus bias the occluder 608 distally away from the proximal end 614 of the spring sleeve 610. This, in turn, can bias the arms 506 of the ram 502 distally away from the proximal end 614 of the spring sleeve 610, which proximal end 614 can bias the plunger 510 of the ram 502 distally relative to the syringe sleeve 430 and within the syringe cavity 404.

Compression spring 606 may be made of any suitable material, such as, but not limited to, steel wire, stainless steel, and spring steel. The spring rate of compression spring 606 may be selected to deliver the appropriate force based on formulation viscosity, needle selection, volume, and desired injection time as described above. In some variations, for example, compression spring 606 may be configured to transmit a force of up to about 5N, about 10N, about 15N, about 20N, about 25N, about 30N, about 35N, about 40N, about 45N, about 50N, about 55N, about 60N, about 65N, about 70N, about 75N, about 80N, about 85N, or about 90N when initially beginning to expand. Fig. 21 shows an illustrative graph of the user force required to perform an injection using an injection device having a force assembly similar to force assembly 106 of injection device 100, showing an initial actuation force and a relatively stable spring decay. The graph shows a liquid with a viscosity of about 9cP injected through a 27ga thin-walled needle, where the seal displaces the contents of the reservoir by about 6mm/s, which typically requires a force of about 15N. However, as seen in this graph, a user force of about 4 to 6N is required, representing a complex multiplication factor of around 3. It should be noted that this graph only illustrates the force requirements of similar devices and is not meant to indicate that the injection device 100 may or must be in accordance with this representation.

As noted above, the rate control assembly of the power assembly may sometimes include a brake assembly that can slow, limit, or inhibit the force provided by the stored energy source to displace the contents of the reservoir of the syringe. In some variations, the rate control assembly is movable between a closed configuration and an open configuration. The rate control assembly may stop or reduce displacement of the contents of the reservoir of the syringe when the rate control assembly is in the closed configuration. The rate control assembly may not restrict or inhibit displacement of the contents of the reservoir of the syringe when the rate control assembly is in the open configuration. In some variations, the rate control assembly may be configured to limit or restrict displacement of the contents of the reservoir of the syringe when in the closed configuration by limiting or inhibiting distal movement of the plunger within the syringe cavity. When in the open configuration, the rate control assembly may not limit or restrict distal movement of the plunger within the syringe cavity, thereby allowing the stored energy source to act on the plunger to move it distally relative to and within the syringe cavity, which may move a seal of the syringe distally within the syringe cavity to displace the contents of the reservoir through the lumen of the needle.

The rate control assembly may be a braking assembly. In some variations, the force generated by the rate control assembly and/or another component of the injection device 100 may counteract or partially or completely resist the force from the stored energy source. In some variations, the brake assembly may be friction based. That is, when the rate control assembly is in the closed configuration, friction between the rate control assembly and another component of the injection device 100 may counteract or partially or completely resist the force from the stored energy source. In some variations, the force when the rate control element is in the closed configuration (e.g., friction between the rate control assembly in the closed configuration and another component of the injection device 100) may completely counteract or resist the force from the stored energy source, thereby preventing distal movement of the plunger 510 within the syringe cavity 404 of the syringe 104. In other variations, the force (e.g., friction between the rate control assembly in the closed configuration and another component of the injection device) may partially counteract or resist the force from the stored energy source, thereby inhibiting distal movement of the plunger within the syringe cavity due to the stored energy source. In some variations, when the rate control assembly is in the open configuration, there may be no force against the stored energy source (e.g., friction between the rate control assembly and another component of the injection device 100), which may allow the stored energy source to move the plunger 510 distally within the syringe cavity 404 of the syringe 104. In other variations, there may be a force against the stored energy source (e.g., friction between the rate control assembly and another component of the injection device 100), but this force may be less than the force required to completely prevent the stored energy source from acting on the plunger 510.

As shown in fig. 9, the rate control component 604 may include the occluder 608 described above. The occluder 608 is reversibly and selectively movable between an open configuration and a closed configuration. When the clutch 608 is in the closed configuration, friction between the clutch 608 and the syringe barrel 430 may counteract or partially or completely resist the distal force from the compression spring 606. This friction may be due to contact between the internal protrusion 628 of the clutch 608 and the syringe barrel 430. The inner protrusions 628 may be configured such that, when the clutch 608 is inverted such that the longitudinal axis 630 passing from the inner cavity 626 is displaced from the longitudinal axis 144 of the housing 102 (and thus from the longitudinal axis 470 of the syringe barrel 430), the inner protrusions 628 come into contact with the syringe barrel 430 with a force sufficient to create sufficient friction to counteract or partially or completely resist the distal force from the compression spring 606. While fig. 8A-8B illustrate the occluder 608 as including three inner protrusions 628 spaced generally equidistantly around the circumference of the lumen 626, it should be appreciated that in other variations the occluder may include other numbers of inner protrusions and/or arrangements. For example, in some variations, the occluder may comprise two or four internal projections equally spaced around the circumference of the lumen.

When the occluder 608 is in an open configuration, a longitudinal axis 630 passing through the lumen 626 of the body 618 of the occluder 608 can rotate from the open configuration toward a position parallel to the longitudinal axis 144 of the housing 102 (and thus toward a position parallel to the longitudinal axis 470 of the syringe sleeve 430). While in some cases the occluder 608 may be rotatable so that the longitudinal axis 630 may be parallel to the longitudinal axis 144 of the housing, the longitudinal axis 630 need not be rotated parallel to the longitudinal axis 144 in order to be in the open configuration. Once rotated to the open configuration, the inner protrusions 628 may not contact the syringe barrel 430. Thus, there may be no friction between the clutch 608 and the syringe barrel 430. In some variations, the clutch 608 may also, but need not, have an intermediate configuration (not shown) in which there is friction between the clutch 608 and the syringe barrel 430, but the friction between the clutch 608 and the syringe barrel 430 may be less than the distal force from the compression spring 606. It will be appreciated that some variations of the injection device described herein may not have a syringe sleeve, but in these variations there may be friction between the inner protrusion 628 and the outer surface 512 of the syringe body 402 when the occluder is in the closed configuration. While the force in the embodiment shown in fig. 9 is due to friction, it should be appreciated that in other variations, the force may be due to another form of interaction of the brake assembly with another component of the injection device. For example, in some variations, the occluder may comprise one or more features (e.g., ridges or teeth) configured to mechanically interact or interface with one or more features (e.g., ridges or teeth) of the syringe barrel, such that a force may be generated that may partially or fully resist the force from the stored energy source.

In some variations, the rate control assembly 604 may be biased toward the closed position, such as by a distal force on the occluder 608 that acts radially asymmetrically on the occluder 608. In the power assembly 106, the occluder 608 can be biased toward the closed configuration by a compression spring 606. The force from the compression spring 606 biasing the distal lip 612 of the spring sleeve 610 away from the proximal lip 454 of the syringe sleeve 430 may cause the distal lip 612 of the spring sleeve 610 to push distally against the proximal protrusion 620 of the occluder 608 as described above. The proximal protrusion 620 of the occluder 608 may extend less than 180 degrees around the body 618 of the occluder 608 on a first side 632, and thus distal force on the proximal protrusion 620 of the occluder 608 from the distal lip 612 of the spring sleeve 610 may tilt the occluder 608 so that the first side 632 may move distally relative to another second side 634 of the occluder 608. The longitudinal axis 630 passing from the lumen 626 of the occluder 608 is thus rotatable relative to the longitudinal axis 144 of the housing 102. This may move the clutch 608 to the closed configuration and the internal protrusion 628 of the clutch 608 contacts the syringe barrel 430 as described above. It should be appreciated that while the proximal protrusion 620 extends about 40 degrees and has a width of about 8mm around the body 618 of the occluder 608 in the embodiment of the occluder 608 shown in figures 8A-8B, in other variations the proximal protrusion 620 may extend more or less (e.g., about 10 degrees, about 20 degrees, about 40 degrees, about 60 degrees, about 80 degrees) around the occluder 608.

The rate control assembly 604 may have an inactive configuration (shown in fig. 7) in addition to the open and closed configurations. In the inactivated configuration, the clutch 608 may be retained by the interlock 436 such that it resists movement relative to the interlock 436. The interlock 436 may include a bite interlock 448, which may include a tab 466 that may extend inwardly from a distal end of the bite interlock 448. The tab 466 can be configured to mate with the protrusion 676 of the occluder 608. The clutch interlock 558 may prevent movement of the clutch 608 relative to the interlock 436 when the tabs 466 mate with the projections 676. As shown in fig. 8A, the protrusion 676 may include a U-shaped hook to which the tab 466 may be attached, as shown in fig. 7. The tab 466 can prevent distal movement of the protrusion 676, and thus the clutch 608, relative to the interlock 436. The rate control assembly 604 may be released from the unactivated configuration by distal movement of the syringe 104. In the variation shown in fig. 7, the clutch 608 may be released from the interlock 436 by the proximal lip 452 of the syringe body 402. As the proximal lip 452 moves distally relative to the interlock 436 as the syringe 104 moves toward the extended configuration, the proximal lip 452 may press against the tab 466 of the bite interlock 448, thereby pushing it radially outward. When the tab 466 is pushed radially outward, it can move outward through the opening in the clevis of the protrusion 676 and can disengage from the protrusion 676. The clutch 608 may thus no longer be held in place by the interlock 436. While the variation shown in fig. 7 includes two clutch interlocks 448 configured to mate with the two projections 676, it should be appreciated that in other variations, the interlocks 436 may include fewer (e.g., zero or one) or more (e.g., three, four, five or more) clutch interlocks and/or projections.

The occluder 608 can be moved to the open configuration by rotating the occluder 608 so that a longitudinal axis 630 passing from the lumen 626 of the body 618 of the occluder 608 moves toward a position parallel to the longitudinal axis 144 of the housing 102 (and thus toward a position parallel to the longitudinal axis 470 of the syringe sleeve 430). As described above, although the occluder 608 may be rotatable in some cases such that the longitudinal axis 630 may be parallel to the longitudinal axis 144 of the housing, the longitudinal axis 630 need not be rotated parallel to the longitudinal axis 144 in order to be in the open configuration. In some variations, the occluder 608 can be moved from a closed configuration to an open configuration by applying a distal force on the second side 634 of the occluder 608. Such distal forces may counteract or partially or completely resist distal forces on the proximal protrusion 620 of the occluder 608 from the distal lip 612 of the spring sleeve 610. Fig. 9 shows one example of an actuation rod 636 that can apply such a distal force. The actuation rod 636 is selectively and reversibly movable between an advanced position, in which it may engage the occluder 608 at a contact point 642 on the second side 634 to urge it toward the open configuration, and a retracted position, in which it may not engage the occluder 608, thereby placing the occluder 608 in the closed configuration. The distal end 644 of the actuation rod 636 may be configured to engage the second side 634 of the occluder 608 at a contact point 642. In some variations, the contact point 642 may optionally include a recessed area to assist in alignment of the actuation rod 636 and the clutch 608. In some variations, the distal end 644 of the actuation rod 636 may optionally include one or more features for facilitating engagement with the contact point 642 of the occluder 608. When actuation rod 636 is forced against the bite 608 at contact point 642, actuation rod 636 can tilt the bite 608 into the open configuration (described above). This may occur when the distal end 644 of the actuation rod 636 presses down on the contact point 642 with sufficient force to counteract or partially or completely resist the force from the compression spring 606 on the proximal protrusion of the occluder 608.

When the syringe 104 is in the extended configuration (described above), the actuation rod 636 can be selectively and reversibly moved between the advanced and retracted positions by applying a distal force to the proximal housing 108. When a distal force is applied to the proximal housing 108 while the distal housing 110 is held in place (e.g., by pressing the distal end 158 of the nose 116 of the distal housing 110 against the patient's tissue) and the syringe 104 is in the extended position, the proximal housing 108 and the actuation rod 636 can move distally relative to the bite 608. The force on the contact point 642 of the occluder 608 from the distal end 644 of the actuation rod 636 may cause the occluder 608 to move to the open configuration as described above. When the occluder 608 is in an open configuration, both a distal force applied to the distal end of the housing and a distal force from the compression spring 606 can urge the occluder 608 distally. This, in turn, can drive the plunger 510 distally via the arm 506 of the ram 502, which can drive the seal 410 distally to displace the contents of the reservoir 414 through the lumen 408 of the needle 406 as described above.

In some variations, the actuation rod 636 may be movable between an advanced position and a retracted position relative to the bite 608 by a distal force on the proximal housing 108, as the relative positions of the ram 502 and the actuation rod 636 may be variable. In some variations, actuation rod 636 may comprise an elongated rod 638 having a proximal end 640 fixedly attached to proximal housing 108. While the actuation rod 636 is shown in fig. 9 as being attached to the inner surface 186 of the end cap 118 of the proximal housing 108, it should be understood that the actuation rod 636 may be fixed to the proximal housing 108 at other locations and via other methods in other variations, or may be integral with the proximal housing 108 in other variations. In contrast, the ram 502 can have an extended position and a retracted position relative to the actuation rod 636 and/or the proximal yoke 108. In one variation, the connecting rod 508 of the ram may be nested within the bore 646 of the actuating rod 636 so as to be slidable between an extended position and a retracted position within the bore 646. In another variation (not shown), the proximal end of the ram is slidable between an extended position and a retracted position within a receiving recess located inside the end cap. In some variations, ram 502 may be biased toward an extended position relative to the proximal end of proximal housing 108. The bias may be due to a compression spring 526. More specifically, the compression spring 526 may be slidably fitted around the link 508 of the hammer 502. Ram 502 may be biased toward an extended position relative to actuation rod 636 by a compression spring 526, which compression spring 526 may be slidably fitted around a connecting rod 508 between plunger 510 and actuation rod 636. In other variations (not shown) where the ram is directly connected to the end cap, the proximal end of the compression spring may be in contact with or attached to a portion of the end cap and the distal end of the compression spring may be in contact with a portion of the ram. Thus, compression spring 526 may bias ram 502 and proximal housing 108 away from each other, thereby biasing ram 502 toward the extended position. It should be appreciated that the compression spring 526 may be in other positions to bias the ram 502 and the proximal housing 108 away from each other.

Thus, when the syringe 104 is in the extended position (described above), the actuation rod 636 can be selectively and reversibly moved between the advanced position and the retracted position by applying a distal force to the proximal housing 108, thereby moving the ram 502 relative to the actuation rod 636 from the extended position to the retracted position.

If the distal force on proximal housing 108 is released, the bias of ram 502 toward the extended configuration relative to actuation rod 636 due to compression spring 526 may move proximal housing 107 and actuation rod 636 distally away from ram 502. However, the syringe 104 may remain in place relative to the syringe barrel 430, and the ram 502 may remain in place relative to the syringe 104. Thus, the actuation rod 636 can be moved from the advanced position to the retracted position to move distally away from the clutch 608 so that it no longer contacts the clutch 608 at contact point 642. Avoiding the application of a distal force at contact point 642 may return the occluder 608 to the closed configuration described above. This may allow the user to selectively and reversibly start and stop the injection process or increase or decrease its speed.

In some variations, but without wishing to be bound by this theory, the amount of distal force that may be applied to the second side of the occluder having a similar design as occluder 608 in order to move the occluder from a closed configuration to an open configuration may be mathematically described in a two-dimensional model as

Where U is the applied distal force, S is the force on the occluder from the compression spring, μ is the coefficient of friction between the syringe barrel and occluder, and e, G, d, t and G represent the distances schematically shown in figure 2A. In models where there are three points of contact between the occluder and syringe barrel, the distal force that can be applied to the second side of the occluder to move it from the closed configuration to the open configuration can similarly be described mathematically as

Where θ represents the angle of the contact point as schematically shown in fig. 24B. Of course, it should be understood that these formulas describe a highly simplified model and are not likely to represent the actual force required to move the occluder 608 described herein from a closed configuration to an open configuration.

In some variations, injection device 100 may include an auto-completion mechanism that may automatically displace the entire volume of reservoir 414 through lumen 408 of needle 406 within certain tolerances of a full injection (e.g., within about 85% of an injection, within about 90% of an injection, within about 95% of an injection, or more, or within about 1mm of a full displacement, about 2mm of a full displacement, about 3mm of a full displacement, or within about 4mm of a full displacement, etc.) regardless of the distal force applied by the user to proximal housing 108. In some variations, auto-completion may be caused by the fact that friction is no longer generated by the clutch 608 and the syringe sleeve 430 once the clutch 608 is moved along the distal portion 434 of the syringe sleeve to a particular distal point. For example, the distal portion 434 of the syringe barrel 430 may include an area near its distal end having a smaller diameter (or maximum distance transverse to the longitudinal axis) than the remainder of the distal portion 434 of the syringe barrel 430 so that when the occluder 608 moves distally to reach this area, the occluder 608 may no longer contact the syringe barrel 430. Thus, there may be no friction between the clutch 608 and the syringe barrel 430, and thus no force against the distal force from the compression spring 606. As a result, dosing can be done automatically. As another example, instead of the distal portion 434 having a smaller full diameter than the area near its distal end, the distal portion 434 of the syringe sleeve 430 may include an inside groove where the clutch 608 will contact the syringe sleeve 430 (e.g., at the location of the inner protrusion 628), which eliminates or reduces friction between the clutch 608 and the syringe sleeve 430 to cause auto-completion.

In some variations, one or more of the elements of the injection device 100 may optionally include a blocking feature to properly orient the elements relative to one another. In some variations, the elements of the injection device 100 may include longitudinal ribs and grooves (e.g., narrow grooves molded into the interior of the proximal housing 108 and short mating ribs on the exterior of the distal housing 110) that may engage to provide alignment and also prevent rotation of the elements relative to each other once engaged. In some variations, the elements of the injection device 100 may include one or more (e.g., two, three, four, five, or more) teeth on a first element and corresponding one or more (e.g., two, three, four, five, or more) grooves in a second element, wherein each tooth and groove is configured to engage when the first and second grooves are properly aligned.

Another embodiment of an injection device 700 is shown in fig. 10, 11A-11B, and 12A-12F, and includes a housing 702, a syringe 704, and a power assembly 706. The housing 702 may be similar to the housing 102 described above with respect to the injection device 100 and may have the same components, configuration, and function. However, as shown in fig. 10, the proximal housing 708 and the distal housing 710 may have an elliptical cross-section that may receive the force assembly 706 described below. The oval shape may also have certain benefits, including having an ergonomic form, allowing easy viewing of the contents of the syringe, and preventing rolling of the device while being handled or stored. In some variations, the minor axis of the cross-section of the housing 702 may be less than or equal to about 20mm, about 25mm, about 30mm, about 35mm, or about 40 mm. Additionally or alternatively, in some variations, the viewing region 724 may include an opening 760 in the distal housing 110, which may have a rounded rectangle shape.

In some variations, the housing 702 may optionally further include a cap 772, which cap 772 may be similar to the cap 148 described above with respect to the injection device 100 and may have the same components and functions as described above. Fig. 11A-11B illustrate side views of the injection device 700 with the cap 772 attached and removed, respectively. The cap 772 can include a viewing area 774 that can coincide with the viewing area 724 of the distal housing when the cap 772 is attached to the remainder of the housing 702.

Fig. 12A-12F show longitudinal cross-sectional views of injection device 700 at various stages of use. Fig. 12A shows the device before use. Fig. 12B shows the device with the rigid needle shield and cap removed. Fig. 12C shows the device with the syringe in the extended position. Fig. 12D shows the device with the plunger moved to the distal position within the syringe cavity. Fig. 12E shows the device with the dose tip indicator in an activated configuration. Fig. 12F shows the needle shield extended device. Fig. 13A-13C show longitudinal cross-sectional views of the distal portion of the injection device 700 showing the needle shield assembly. Similar to the injection device 100, the injection device 700 may include a needle safety assembly 800 that may be moved between a retracted position (shown in fig. 13A-13B) and an extended position (shown in fig. 13C-13D) as described in detail above with respect to the needle safety assembly 200. As shown in fig. 13A-13D, the needle safety assembly 800 may include an extendable needle shield 802, a biasing element 818, and a locking assembly 826 having the same components, locations, and functions as described above with respect to the needle safety assembly 800. However, with respect to the biasing element, the biasing element 818 can include a compression spring 820, and the compression spring 820 can have a cylindrical shape and can be nested within the lumen 808 of the needle shield 802. The proximal end 822 of the compression spring 820 may contact a ledge 776 extending radially outward from the inner sheath 762 of the nose 716, and the distal end 824 of the compression spring 820 may contact the lip 816 extending radially inward from the needle shield 802. While the lip 816 is shown in fig. 13A-13D as being located at the distal end 812 of the needle shield 802, it should be appreciated that in other variations, the lip may extend from a location proximal to the distal end 812 of the needle shield 802. In some variations, the proximal end 822 of the compression spring 820 may be fixedly attached to the inner sheath 762 of the nose 716, but need not be (e.g., the compression spring may rest against the nose 716 but may not be attached). It should also be appreciated that in other variations, the proximal end 822 of the compression spring 820 may contact or be fixedly attached to a portion of the distal housing 710.

In some variations, the locking assembly 826 of the needle safety assembly 800 of the injection device 700, similar to the locking assembly 226 of the injection device 100, may retain the needle shield 802 in the retracted and/or extended position. In some variations, the locking assembly 826 may include one or more latches 828, and the latches 828 may have the same components, locations, and functions as described above with respect to the injection device 100. However, in some variations, the latch 828 may be configured to mate with a portion of the nose 716 such that, when mated, the latch 828 prevents movement of the needle shield 802 relative to the distal housing 710. As shown in fig. 13A-13D, the nose 176 may include an inner sheath 762, and the inner sheath 762 may include four proximal slots 764. Four proximal slots 764 may be located on the inner sheath 762 such that when the tabs 834 of the latch 828 mate with the proximal slots 764, the needle shield 802 may be in a retracted position. When the tabs 834 mate with the proximal slots 764, the elongate portions 830 of the latches 828 may be flush with the outer surface 958 of the syringe barrel 930 (described below) and the tabs 834 of the latches 828 may be radially inserted into the proximal slots 764. The locking assembly 826 may prevent distal movement due to the biasing force from the biasing element 818 due to the proximally directed force applied to the distal surface of the tab 834 by the distal surface of the proximal slot 764.

The locking assembly 826 may be configured such that the needle shield 802 may be unlocked from the retracted position by distal movement of the syringe 704 (e.g., the locking assembly 826 may no longer hold the needle shield 802 in the retracted position). In some variations, the tabs 834 may be configured such that they can be released from the proximal slots 764 by distal movement of the injector body 902 of the injector 704 relative to the nose 716. For example, in the variation shown in fig. 13A-13D, the tab 834 can have a triangular, proximally tapering shape. Thus, as the injector body 902 of the injector 704 moves distally relative to the nose 716 and within the inner sheath 762, the distal end of the injector body 902 may engage the inner surface of the tab 834 that protrudes through the proximal slot 764. As the syringe body 902 of the syringe 704 continues to slide distally along the inner surface of the inner sheath 762 of the nose 716, the outer surface of the syringe body 902 gradually pushes the tab 834 further radially out of the proximal slot 764. Once the outer surface of the syringe body 902 has fully radially projected the tab 834 from the proximal slot 764, the tab 834 may no longer mate with the proximal slot 764 and may no longer prevent distal movement of the needle shield 802 relative to the distal housing 710. Similar to the needle shield 202 of the injection device 100, when the needle shield 802 of the injection device 700 is unlocked from the retracted position, it may be moved to the extended position if an appropriate force is applied, or such a force may be partially or fully counteracted by an opposing force, as described in detail above with respect to the needle shield 202. Likewise, the needle shield 802 of the injection device 700 may be flaked from the retracted position just prior to the distal tip 924 of the needle 906 of the syringe 704 extending from the distal end 758 of the nose 716, as described in detail above with respect to the needle shield 202.

Similarly, the needle shield 802 of the injection device 700 may additionally or alternatively be configured to be locked in the extended position once moved to the extended position, as described in detail with respect to the needle shield 202. However, in the variation shown in fig. 13A-13D, the inner sheath 762 of the nose 716 may include four distal slots 770 configured to mate with the tabs 834 of the latch 828 of the lock assembly 826. As shown in fig. 13C-13D, a distal slot 770 may be located on the inner sheath 762 to coincide with the location of the tab 834 when the needle shield 802 is in the extended position. When the needle shield 802 is moved to the extended position, the tabs 834 on the latch 828 can mate with the distal slots 770. When the tabs 834 on the latch 828 mate with the distal slot 770, the locking assembly 826 can prevent movement of the needle shield 802 relative to the nose 716.

The housing 702 may also include an indicator, similar to the indicators described with respect to the injection device 100, that may indicate the progress or completion of an injection, as described in detail above, and may have an activated configuration and an inactivated configuration. Fig. 14A-14B are longitudinal cross-sectional and elevational side views, respectively, of a proximal portion of an injection device 700, showing a dose tip indicator 900 having different appearances in relation to an activated configuration and an inactivated configuration, in an inactivated configuration and an activated configuration. In the variation shown in fig. 14A-14B, the indicator 900 can include a ram crossbar 1112 of the ram 1102, described in more detail below. The ram crossbar 1112 may be configured such that at least a portion of the ram crossbar 1112 is visible from the housing of the end cap 718 when the proximal surface 1118 of the ram crossbar 1112 is adjacent to the inner surface 768 of the end cap 718 of the proximal housing 708. In some variations, at least a portion of the ram crossbar 1112 may have a color or pigment that is more easily noticeable, such as, but not limited to, red, yellow, orange, green, magenta, blue, and the like. To see the ram crossbar 1112 through at least a portion of the end cap 718, in some variations, at least a portion of the end cap 718 may be translucent or transparent. In variations where at least a portion of the end cap 718 is translucent, the translucency may be such that: when the ram rail 1112 is adjacent the viewing portion, the color of the ram rail 1112 can be sensed through the end cap 718.

The indicator 900 may also include a biasing element 920, which may be configured to bias the indicator 900 toward the inactivated configuration. As shown in fig. 14A-14B, in some variations, the biasing element 920 may include a lock spring 1246, which is described in more detail later with respect to the force assembly 706 of the injection device 700. The proximal end 1258 of the lock spring 1246 may be attached to or in contact with the inner surface 768 of the end cap 718 of the proximal housing 708, while the distal end 1256 of the lock spring 1246 may be attached to or in contact with a portion of the ram 1102, as described in more detail below. The lock spring 1246 may thus bias the ram crossbar 1112 away from the inner surface 768 of the end cap 718 of the proximal housing 708. When the plunger 1110 has traveled the full length of the syringe cavity 904, the biasing of the ram crossbar 1112 away from the inner surface 768 of the end cap 718 may be overcome by a distal force on the proximal housing 808 when a complete injection of the contents of the reservoir 914 is complete, as described in more detail below.

The injector 704 of the injection device 700 may be similar to the injector 104 described above with respect to the injection device 100 and may have the same components, locations, and functions as described above. The injection device 700 may also include a syringe barrel 930. Fig. 15 shows a perspective view of the syringe 704 and syringe barrel 930 of the injection device 700. A syringe sleeve 930 may attach the syringe body 902 of the syringe 704 to a ram interlock 1226 (described in more detail below). The proximal lip 952 of the syringe body 902 may rest on the proximal lip 954 of the syringe sleeve 930. The proximal lip 954 of the syringe sleeve 930 may include four latches 964, and the latches 964 may be configured to attach to four corresponding recesses located distal to the ram interlock 1226 (described below). Thus, when the syringe sleeve 930 is attached to the ram interlock 1226, the proximal lip 952 of the syringe body 902 may be secured between the proximal lip 954 of the syringe sleeve 930 and the ram interlock 1226, thereby causing the syringe body 902 to resist distal movement relative to the syringe sleeve 930. The syringe barrel may comprise any suitable material, but in some variations, the syringe barrel 930 may comprise a plastic material.

Fig. 16A-16B show a cut-away elevational side view and a longitudinal cross-sectional view, respectively, of the ram and force assembly of the injection device of fig. 10. As in ram 502 described with respect to injection device 100, ram 1102 may be directly or indirectly connected with proximal housing 708 such that movement of proximal housing 708 may be transferred to ram 1102. Ram 1102 can be configured to translate the distal force on proximal housing 708 into different motions depending on the stage of the injection process. In the first stage, the distal force on the proximal housing 708 may be transferred into the distal movement of the syringe 704 and the power assembly 706 relative to the distal housing 710. In a second stage, distal forces on the proximal housing 708 may be transferred to the contents of the reservoir 914 of the syringe 704 (e.g., a formulation containing a therapeutic agent) to be displaced through the lumen 908 of the needle 906.

In some variations, the ram 1102 may be configured such that these actions of the distal force on the proximal housing 708 may occur in the order described above. That is, the ram 1102 can be configured such that a distal force on the proximal housing 708 can be first transferred into distal movement of the syringe 704 and the force assembly 706 relative to the distal housing 710, and then second transferred into displacement of the contents of the reservoir 914 of the syringe 704 (e.g., a formulation containing a therapeutic agent) through the lumen 906 of the needle 908. This may be desirable, for example, because it may allow the syringe 704 to move distally so that the needle 906 may pierce the patient's tissue before the contents of the syringe cavity 904 displace through the lumen 908 of the needle 906.

In some variations, the sequence of application of the distal force on the proximal housing 708 may be attributable to different amounts of force required for each movement. For example, when the force on proximal housing 708 is above a first threshold (e.g., above about 1N, above about 2N, above about 3N, above about 4N, above about 5N, above about 6N, above about 7N, or higher), ram 1102 can transfer the distal force on proximal housing 708 into the distal motion of syringe 704 and force assembly 706 relative to distal housing 710; and when the force on the proximal housing 708 is above a second, higher threshold (e.g., above about 1N, above about 2N, above about 4N, above about 6N, above about 8N, above about 10N, above about 12N, above about 14N, or higher), the ram 1102 may transfer the distal force on the proximal housing 708 into displacement of the contents of the reservoir 914 of the syringe 704 through the lumen 908 of the needle 906. In some variations, the first threshold may be attributable to a proximal force from a flange on the base stop cover 1126 (described below) preventing distal movement of the ram interlock 1226 to which the syringe 704 is attached, as described in detail below. The second threshold may be attributable to the force required to pass over a second set of flanges 1296 (described below) and move the rate control assembly 1204 of the force assembly 706 to the open configuration, as described in detail below. There may also be an intermediate threshold that may need to be overcome in order for the needle 906 to protrude beyond the distal end 758 of the nose cone 716. In some variations, this intermediate threshold may be attributable to two bends on ram interlock 1226, which may interface with two recesses on distal housing 710. It should be appreciated that in other variations, ram 1102 may transmit the distal force on proximal housing 708 into different motions in different orders and through different mechanisms. For example, in some variations, the application of the distal force may be selectable by manual selection by the user. It should also be appreciated that the ram may transmit the distal force on the proximal housing into a more or less different motion.

The ram 1102 can include a central portion that includes a plunger 1110 and a ram crossbar 1112 at a proximal end 1114 of the plunger 1110. Plunger 1110 can be configured to slide within syringe cavity 904. The distal end 1116 of the plunger 1110 may be configured to engage the seal 910 of the syringe 704. If the plunger 1110 is moved distally relative to and within the syringe cavity 904, the plunger 1110 can push the seal 910 distally relative to and within the syringe cavity 904. This movement of the seal 910 may reduce the volume of the reservoir 914 containing the formulation containing the therapeutic or diagnostic agent. Thus, distal movement of the plunger 1110 and, in turn, the seal 910 relative to and within the syringe cavity 904 can displace the contents of the reservoir 914 through the lumen 908 of the needle 906. The ram crossbar 1112 may be attached distally thereof to the proximal end 1114 of the plunger 1110. The proximal surface 1118 of the ram crossbar 1112 may be configured to be positioned adjacent to the inner surface 768 of the end cap 718 of the proximal housing 708 such that the ram crossbar 1112 may function as an indicator as described above. The ram 1102 can include an internal bore 1120 extending through the ram crossbar 1112 and the plunger 1110, and can have a proximal opening 1122 at the proximal surface 1118 of the ram crossbar 1112 and a closed distal end 1124 near the distal end 1116 of the plunger 1110. The bore 1120 may be configured to receive at least a distal portion of a locking spring 1246 (described in more detail below). The proximal end 1258 of the locking spring 1246 may be attached to or in contact with the inner surface 768 of the end cap 718 of the proximal housing 708, while the distal end 1256 of the locking spring 1246 may be attached to or in contact with the distal end 1124 of the internal bore 1120 of the plunger 1110. The locking spring 1246 can thus be configured to transmit the motion of the proximal housing 708 to the ram 1102 in addition to being part of the rate control assembly 1204 of the force assembly 706, which serves as a means for transmitting the motion of the proximal housing 708 to the ram 1102. Plunger 1110 may also include two recesses 1140 at its distal end 1116. These recesses 1140 may be configured to engage two flanges 1296 extending from a central lumen 1228 of a ram interlock 1226 (described in more detail below). Flange 1296 can include an inwardly facing proximal tab 1298, and proximal tab 1298 can be configured to engage recess 1140, which can prevent distal movement of plunger 1110 relative to ram interlock 1226.

The injection device 700 may also include a base stop cover 1126. The distal side of base stop cover 1126 may be attached to the proximal side of ram interlock 1226 (described below). As shown in more detail in fig. 16A-16B and in fig. 16C, the base stop cover 1126 may include two flanges 1130 located on opposite sides of the body 1132 of the base stop cover 1126. The flange 1130 may extend proximally and outwardly from the body 1132 and may have a proximal tab 1134. After the injection device 700 has been assembled, the proximal tabs 1134 may engage with recesses 780 on the inner surface of the proximal housing 708 so as to inhibit proximal movement of the proximal housing 708 relative to the distal housing 710. The body 1132 of the base stop cover 1126 may also include a central lumen 1136 and two side lumens 1138. Central lumen 1136 may be configured to allow plunger 1110 of ram 1102 to move therethrough. Central lumen 1136 may also include two recesses 1142 (described below) configured to allow flange 1296 of ram interlock 1126 to move therethrough. The two side lumens 1138 may be configured to allow a portion of the force assembly 706 to move therethrough, as described below. The base stop cover 1126 may comprise any suitable material, but in some variations the base stop cover 1126 may comprise a plastic material.

Injection device 700 may also include ram interlock 1226. Ram interlock 1226, shown in more detail in fig. 16D, can include a central lumen 1228 configured to allow travel of plunger 1110 of ram 1102 therethrough, and can include one side lumen 1236 on each of two opposite sides of central lumen 1228, each side lumen 1236 configured to allow travel of one of two compound springs 1218 therethrough, as described in more detail below. Ram interlock 1126 may also include two flanges 1296 extending from central lumen 1228, which may include inwardly facing proximal tabs 1298. In an initial configuration, an inwardly facing proximal tab 1298 of flange 1296 of ram interlock 1126 may engage recess 1140 of plunger 1110 as described above and shown in fig. 16B, which may cause plunger 1110 to be prevented from distal movement relative to ram interlock 1226. Flange 1296 can be prevented from bending radially outward (such that proximal tab 1298 can be separated from recess 1140 of plunger 1110, which would allow plunger 1110 to move distally relative to ram interlock 1226) because in the initial configuration, the distal face of base stop cover 1126 is seated against the proximal face of ram interlock 1226 such that flange 1296 of ram interlock 1226 is located within recess 1142 of base stop cover 1126. The base stop cap 1126 may thus exert radially inward pressure on the flange 1296 to prevent them from moving radially outward. This may create hoop stress within central lumen 1228 of ram interlock 1226.

Application of a distal force on proximal housing 708 may cause proximal housing 708 to move distally. If the distal shell 710 is held in place (e.g., by pressing the distal end 758 of the nose 716 of the distal shell 710 against the patient's tissue), the proximal shell 708 may move distally relative to the distal shell 710. Movement of the proximal housing 708 may be transferred via lock spring 1246 to slide the force assembly 706 and syringe 704 distally relative to the distal housing 710 if the distal force on the proximal housing 708 is above a necessary force threshold. More specifically, a distal force on proximal housing 708 can cause distal movement of lock spring 1246 and, in turn, force assembly 706. Distal movement of the power assembly 706 may in turn cause distal movement of the syringe 704. This may move the syringe 704 from a retracted position (shown in fig. 12A-12B) to an extended position (shown in fig. 12D-12F), as described above with respect to the syringe 103 of the injection device 100. As the distal tip 924 of the needle 906 approaches the distal opening 712 of the nose 716, the needle shield 802 of the needle safety assembly 800 may be unlocked from the retracted position, as described in detail above and shown in fig. 13A-13D. As the distal tip 924 of the needle 906 moves to protrude beyond the distal end 758 of the nose 716, the needle 906 may pierce tissue pressed against the distal end 758 of the nose 716. The syringe 704 may continue to move distally relative to the distal housing 710 until the syringe 704 has reached an extended position, at which point distal movement of the syringe 704 may be stopped by engagement of the syringe sleeve 930 with a portion of the nose 716. In the extended position, the distal tip 924 of the needle 906 may have reached the desired depth as described above. In some variations, the injection device 700 may include an insertion stop that may cause movement of the distal tip 924 of the needle 906 to occur at a particular rate during insertion in order to achieve a desired speed of insertion into tissue as described above.

It should be noted that due to the relative amounts of force required to move the force assembly 706 and syringe 704 relative to the distal housing 710 and the ram 1102 relative to the syringe 704, the force assembly 706 and syringe 704 may be moved distally together with the distal force on the proximal housing 708 at a particular injection stage, rather than the force assembly 706 acting on the syringe 704 (e.g., by moving the syringe 1110 distally within the syringe cavity 904 to act on the seal 910 and displace the contents of the reservoir 914). That is, the amount of force required to move the syringe 704 to the extended position may be less than the amount of force required to cause distal movement of the ram 1102 relative to the syringe 704. In some variations, the ram interlock 1226 and base stop cover 1126 may prevent distal movement of the ram 1102 relative to the syringe 704 until the syringe 704 is in the extended position. The flange 1296 of the ram interlock 1226 can be positioned within the recess 1142 of the base stop cover 1126, and the base stop cover 1126 can exert radially inward pressure on the flange 1296 to prevent them from flexing radially outward to separate from the recess 1140 of the plunger 1110, as described above. However, as the syringe 704 moves toward the extended configuration, the proximal housing 708, the power assembly 706, and the ram interlock 1226 can move distally with the syringe 704 relative to the distal housing 710, while the base stop cover 1126 can remain fixed relative to the distal housing 710. Flange 1296 can be configured to have a length of: before the syringes 704 have reached the extended position, they may remain constrained by the base stop cap 1126.

After the power assembly 706 and syringe 704 have been moved distally relative to the distal housing 710 such that the syringe 704 is in the extended position and the distal tip 924 of the needle 906 is at the desired depth and accordingly the flange 1296 of the ram interlock 1226 can no longer be constrained by the base stop cap 1126, if the additional distal force on the proximal housing 708 is greater than the necessary force threshold, that force can be transferred into the distal movement of the ram 1102 relative to the syringe cavity 904. When the force is above the necessary force threshold, the plunger 1110 and seal 910 may move distally within the syringe cavity 904, which may reduce the volume of the reservoir 914 and displace the contents of the reservoir 914 through the lumen 908 of the needle 906, as described above with respect to the syringe 104 of the injection device 100. The distal force on the proximal housing 708 may continue to displace the contents of the reservoir 914 through the lumen 908 of the needle 906 until the seal 910 has traveled to the distal end 918 of the syringe cavity 904 (shown in fig. 12D-12E). In some variations, the threshold force required to move the plunger 1110 and seal 910 distally within the syringe cavity 904 may be attributable to the flange 1296 of the ram interlock 1226. As described above, ram interlock 1126 may include two flanges 1296 extending from central lumen 1228, which may include inwardly facing proximal tabs 1298. In the initial configuration, an inwardly facing proximal tab 1298 of flange 1296 of ram interlock 1126 may engage recess 1140 of plunger 1110, which may cause plunger 1110 to be prevented from distal movement relative to ram interlock 1226. However, when a threshold force is applied, flange 1296 can flex radially outward such that proximal tabs 1298 can disengage from recess 1140 of plunger 1110 and thus can allow plunger 1110 to move distally relative to ram interlock 1226 under the control of a rate control assembly of force assembly 706 described below. If the distal force on proximal housing 108 is released while force assembly 706 and syringe 704 are moved from the retracted position to the extended position, force assembly 706 and syringe 704 may remain in place relative to distal housing 710.

As described above with respect to the force assembly 106 of the injection device 100, the force assembly can provide an injection force sufficient (alone or in addition to the injection force supplied by the user) to inject a particular formulation of a particular volume through a particular sized needle at a particular time, as described in detail with respect to the force assembly 106. Similar to the force assembly 106, the force assembly 706 can include a stored energy source and a rate control assembly. As in the power assembly 106 described with respect to the injection device 100, the power assembly 706 can include a stored energy source 1202 that can be configured to provide a force to displace contents of the reservoir 914 of the syringe 704 through the lumen 908 of the needle 906, and a rate control assembly 1204 that can include a braking assembly that can limit or inhibit the stored energy source 1202 from causing the contents of the reservoir 914 of the syringe 704 to be displaced through the lumen 908 of the needle 906. Returning to fig. 16A-16B, the stored energy source 1202 may include one or more springs to provide an injection force. In the injection device 700, the spring of the stored energy source 1202 may pull the ram 1102 distally to displace the contents of the reservoir 914 of the syringe 704 through the lumen 908 of the needle 906. In some variations, the spring may be a compound spring in order to reduce the overall length of the spring that generates the required force. Such a compound spring may comprise an extension spring coaxially within a compression spring. However, it should be appreciated that in other embodiments, the spring may not include a compound spring, and may instead include, for example, a single extension spring or a single compression spring; furthermore, in other embodiments, the injection device may comprise only one compound spring, or may comprise more than two compound springs, for example two, three, four or more compound springs.

The two compound springs 1218 of the stored energy source 1202 may each have a compression spring 1220 coaxially located about the extension spring 1206. It should be appreciated that in other variations, the extension spring 1206 may be coaxially located within the compression spring 1220. In each of the two compound springs 1218, the proximal end 1222 of the compression spring 1220 may be distal to the proximal end 1214 of the extension spring 1206, and the proximal end 1222 of the compression spring 1220 may be attached to a ram interlock 1226. A proximal end 1214 of extension spring 1206 may be attached to ram crossbar 1112. The distal end 1224 of the compression spring 1220 and the distal end 1216 of the extension spring 1206 may be directly or indirectly connected to each other at a compound spring interface 1230. In some variations, the compound spring interface 1230 may include an intermediate member, such as, but not limited to, a plastic sleeve, which may be engaged with the distal end 1224 of the compression spring 1220 and the distal end 1216 of the extension spring 1206. In other variations, the distal end 1216 of the extension spring 1206 may comprise a wire loop having a larger diameter than the compression spring 1220, and the compression spring 1220 may be inserted into the distal end 1216 of the extension spring 1206 to engage with the compression spring 1220 and the extension spring 1206. In still other variations, the extension spring 1206 and the compression spring 1220 may be formed as a unitary wire using a continuous wire.

The spring rate of extension spring 1206 and compression spring 1220 can be selected to deliver the appropriate force based on formulation viscosity, needle selection, volume, and desired injection time as described above. In some variations, for example, the spring may be configured to transmit a force of up to about 5N, about 10N, about 15N, about 20N, about 25N, about 30N, about 35N, about 40N, about 45N, about 50N, about 55N, about 60N, about 65N, about 70N, about 75N, about 80N, about 85N, or about 90N when composite spring 1218 is initially released. In some variations, compound spring 1218 and/or extension spring 1220 may comprise a steel wire, but it should be appreciated that the springs may be made of any suitable material.

In some variations, composite spring 1218 may additionally include a composite spring sleeve 1232, but need not be. In variations having a composite spring sleeve, the composite spring sleeve 1232 may include a cylindrical wall 1234 that may separate the extension spring 1206 and the compression spring 1220. In some variations, the compound spring sleeve 1232 may assist in providing spring guidance. Composite spring sleeves 1232 may pass through side cavities 1236 on each side of central cavity 1228 of ram interlock 1226, and they may pass through both side cavities 1138 of base stop cover 1126. The distal end 1240 of the composite spring sleeve 1232 may serve as the composite spring interface 1230 and, thus, may have attached thereto both the distal end 1224 of the compression spring 1220 and the distal end 1216 of the extension spring 1206. In some variations, ram interlock 1226 and/or spring sleeve 1232 may comprise a plastic material, but it should be appreciated that ram interlock 1226 and/or spring sleeve 1232 may be made of any suitable material.

The extension spring 1206 may bias the compound spring interface 1230 and the ram crossbar 1112 toward one another, while the compression spring 1220 may bias the ram interlock 1226 and the compound spring interface 1230 away from one another. The combined action of the extension spring 1206 and the compression spring 1220 of the compound spring 1218 may thus bias the ram interlock 1226 and the ram crossbar 1112 toward each other. By biasing the ram interlock 1226 and ram crossbar 1112 toward each other, the compound spring 1218 may thus bias the plunger 1110 distally through the central lumen 1228 of the ram interlock 1226. The plunger 1110 may be configured to slidably fit within the syringe cavity 904 and press against the seal 910, which in turn may displace the contents of the reservoir 914 of the syringe 704 through the lumen 908 of the needle 906, as described in detail above with respect to the syringe 104 of the injection device 100.

However, the distal movement of the plunger 1110 against the seal 910 of the syringe 704 may sometimes be prevented or limited by the rate control assembly 1204. As described above with respect to the injection device 100, the rate control assembly is movable between a closed configuration and an open configuration. The rate control assembly may limit or restrict displacement of the contents of the reservoir of the syringe when the rate control assembly is in the closed configuration. The rate control assembly may not restrict or inhibit displacement of the contents of the reservoir of the syringe when the rate control assembly is in the open configuration. In some variations, the rate control assembly may be configured to limit or restrict displacement of the contents of the reservoir of the syringe when in the closed configuration by limiting or inhibiting distal movement of the plunger within the syringe cavity. When in the open configuration, the rate control assembly may not limit or restrict distal movement of the plunger within the syringe cavity, thereby allowing the stored energy source to act on the plunger to move it distally relative to and within the syringe cavity, which may move a seal of the syringe distally within the syringe cavity to displace the contents of the reservoir through the lumen of the needle.

As shown in fig. 16A, the rate control assembly 1204 may include a cord tensioning system 1242. The cord tensioning system 1242 may prevent the action of the stored energy source 1202 as described above. The cord tensioning system 1242 is reversibly and selectively movable between a tensioned configuration (the "closed" configuration of the rate control assembly) and a released configuration (the "open" configuration of the rate control assembly). Generally, the cord tensioning system 1242 may include a tensioning cord 1244 in addition to the locking spring 1246 and the ram interlock 1226 described above. When the cord tensioning system 1242 is in a tensioned configuration, the locking spring 1246 may create a pulling force on the tensioning cord 1244 of a magnitude sufficient to prevent the ram 1102 from moving distally due to the stored energy source 1202. Sufficient tension in the tensioning line 1244 can be achieved by wrapping the tensioning line 1244 around the tether pile 1288. In some variations, tether pile 1288 may comprise a portion of ram interlock 1226 as described in more detail below. When the cord tensioning system 1242 is in the release configuration, the cord tensioning system 1242 may allow the distal force on the ram 1102 from the compound spring 1218 to drive the plunger 1110 of the ram 1102 distally, as described in more detail below. In some variations, the cord tensioning system 1242 may optionally further include a float 1248, a locking spring collar 1250, and a locking spring cover 1252, which will be described in more detail below.

As shown in fig. 16A-16B, the locking spring 1246 may comprise a compression spring 1254. As described above, at least the distal portion of locking spring 1246 may be located within bore 1120 of plunger 1110. Distal end 1256 of locking spring 1246 may be attached to or in contact with distal end 1124 of bore 1120 of plunger 1110. Alternatively, in some variations, at least the distal portion of the locking spring 1246 may be received in the locking spring collar 1250. The distal end of the locking spring collar 1250 may be located proximal to the distal end 1124 of the inner bore 1120, or in other variations, it may be attached to or in contact with the distal end 1124 of the inner bore 1120. In some variations, the locking spring retainer 1250 may comprise deep drawn metal. In some variations, the locking spring retainer 1250 may include an aperture in its distal end that may allow for the flow of a viscous damping fluid located in the internal bore 1120, and thus may dampen the movement of the locking spring retainer 1250 under the force of the locking spring 1246. The proximal end 1258 of the locking spring 1246 may be attached to or in contact with the inner surface of the end cap 718 of the proximal housing 708. Locking spring 1246 may thus bias plunger 1110 away from end cap 718 of proximal housing 708. In some variations, lock spring 1246 can have a spring rate of about 0.1N/mm to 0.2N/mm, 0.2N/mm to 0.3N/mm, 0.3N/mm to 0.4N/mm, 0.4N/mm to 0.5N/mm, 0.5N/mm to 0.6N/mm, 0.6N/mm to 0.7N/mm, 0.7N/mm to 0.8N/mm, 0.9N/mm to 1N/mm, or greater. In some variations, the proximal end 1258 of the lock spring 1246 may be received in the lock spring cover 1252. For example, in variations where all or a portion of end cap 718 is made of a transparent or translucent material, locking spring cover 1252 may be used to conceal proximal end 1258 of locking spring 1246 from view through end cap 718.

As shown in fig. 17, the rate control assembly 1204 may also include a tensioning cord 1244. The end of the tensioning line 1244 may be attached to a float 1248 that may be fixedly attached to the proximal housing 708 (not shown), while the middle portion of the tensioning line 1244 may be wrapped around the ram interlock 1226 at two points and attached to the distal end 1116 of the plunger 1110 between the two points. It should be appreciated that in some variations, the tensioning line 1244 may be attached directly to the proximal housing 708 rather than to the float. By biasing the plunger 1110 away from the end cap 718 of the proximal housing 708 (not shown), the locking spring 1246 may create a pulling force in the tensioning cord 1244, thereby preventing distal movement of the plunger 1110. More specifically, the float 1248 may be attached to the proximal housing 708 via a latch that may snap into a mating recess in the proximal housing 708. In some variations, the float 1248 may comprise a plastic material, but it should be appreciated that the float 1248 may comprise any suitable material.

A first end 1254 of a tensioning line 1244 may be attached to the float 1248 on a first side of the plunger 1110. The first end 1254 of the tensioning line 1244 may be attached to the float 1248 in any suitable manner. For example, in some variations, the first end 1254 of the tensioning line 1244 may be attached to the float 1248 by being encapsulated in a plastic material, such as by insert molding in the float 1248. In other variations, the first end 1254 of the tensioning line 1244 may be engaged using a lug or collar, which in turn may be attached to a receiving socket in the float 1248. A first portion 1272 of the tensioning line 1244 may extend distally from the float 1248 toward the ram interlock 1226. The ram interlock 1226 can include one or more tether pegs 1288 that can allow the tensioning line 1244 to wrap around the ram interlock 1226 in a manner that creates friction between the tensioning line 1244 and the ram interlock 1226. In some variations, the ram interlock 1226 can include a first protrusion 1264 and a second protrusion 1266 on opposite sides of the ram interlock 1226. The tensioning cord 1244 can have a rounded side 1290 that can wrap around the first protrusion 1264. The tensioning cord 1244 may have a third portion 1276 that may travel from the first protrusion 1264 to the distal end 1116 of the plunger 1110. The distal end 1116 of the plunger 1110 may include one or more features that may allow for a tensioning line 1244 to be attached on its distal end 1116. In some variations, the distal end of the plunger 1110 may include a slot 1756 spanning the distal face 1754 of the plunger 1110, and the fourth portion 1278 of the tensioning line 1244 may be placed through the slot 1756. A fifth portion 1280 of the tensioning line 1244 can exit the slot 1756 of the plunger 1110 and extend toward the second protrusion 1266 (not shown). A sixth portion 1282 of the tensioning line 1244 can be wrapped around the rounded side 1292 of the second protrusion 1266 (not shown). While in the illustrated variation the first and second projections 1264 and 1266 may comprise first and second horizontal cylindrical sections 1268 and 1270 (not shown) with the first and second horizontal cylindrical sections 1268 and 1270 oriented with their rounded sides facing distally, it should be appreciated that the first and second projections 1264 and 1266 of the ram interlock 1226 may be shaped such that the projections are rounded at the point of contact with the tensioning line 1244, and thus may comprise a full cylindrical segment in some variations. Finally, the tensioning line 1244 can have a seventh portion 1284 that can extend proximally from the ram interlock 1226 toward the float 1248, wherein the second end 1256 of the tensioning line 1244 can be attached to the float 1248 on a second side of the plunger 1110 (not shown)). Second end 1256 may be attached to float 1248 in any suitable manner, including in the manner described above with respect to first end 1254. In other variations, the first end 1254 and the second end 1256 may be connected (e.g., the tensioning cord 1244 may be a closed loop, or the first end 1254 and the second end 1256 may be spliced, interwoven, or welded together), and the tensioning cord 1244 may extend around the float 1248 to secure it. In some of these variations, the tensioning line 1244 may be located in a receiving channel in the float 1248.

By winding the tensioning cord 1244 as described above through the slot 1756 on the distal face 1754 of the plunger 1110, the tension in the tensioning cord 1244 may prevent the plunger 1110 from moving distally through the central lumen 1228 of the ram interlock 1226 due to the biasing force from the stored energy source 1202. Due to the friction between the tensioning cord 1244 and the first and second tabs 1264, 1266 of the ram interlock 1226, the cord tensioning system 1242 may resist forces from the stored energy source 1202 greater than may be provided by the locking spring 1246. Under the principles of the winch equation (also known as the Eytelwein equation), the tension on the line (e.g., the tightening line 1244) may be different on either side of the static cylinder (e.g., the first and second projections 1264, 1266 of the ram interlock 1226) so that the holding force on either side of the static cylinder (e.g., the tension supplied by the locking spring 1246) may carry a greater loading force (e.g., the force supplied by the compound spring 1218). The relationship between the holding force and the loading force is governed by the coefficient of friction between the cord and the static cylinder and the angle of wrap-the angle around which the cord contacts the static cylinder. In the cord tensioning system 1242, the tensioning cord 1244 and the ram interlock 1226 may comprise any material having a suitable coefficient of friction, such as, but not limited to, a tensile cord 1244 comprising aramid fibers and a first protrusion 1264 and a second protrusion 1266 comprising polycarbonate. In some variations, the coefficient of friction between the two materials may be about 0.1 to 0.2, about 0.2 to 0.3, about 0.3 to 0.4, about 0.4 to 0.5, or greater. Additionally, it may be desirable for the tensioning line 1244 to comprise a material having suitable ability to maintain a sustained load and resistance to creep and tensile properties, such as, but not limited to, aramid fibers. The tensioning cord 1244 may be wrapped around the first and second tabs 1264, 1266 of the ram interlock 1266 at a wrap angle sufficient to produce the desired relationship between the holding and loading forces. In some variations, the wrap angle may be about 180 degrees. In other variations, the wrap angle may be 360 degrees or more, such as 720 degrees; that is, the tensioning cord 1244 may be wrapped multiple times around the first and second projections 1264, 1266 of the ram interlock 1226.

The cord tensioning system 1242 may be biased toward the tensioned configuration such that when a distal force is not applied to the proximal housing 708, the cord tensioning system 1242 may prevent or limit the stored energy source 1202 from causing the contents of the reservoir 914 of the syringe 704 to be displaced through the lumen 908 of the needle 906 by applying the proximal force to the distal end 1116 of the plunger 1110 of the ram 1102 as described above.

While the cord tensioning system 1242 may be biased toward the tensioned configuration as described above, the cord tensioning system 1242 may be moved toward the released configuration by reducing or releasing the tension on the first portion 1272 and the seventh portion 1284 of the tensioning cord 1244 (described above)). The tension on the first and seventh portions 1272 and 1280 of the tensioning line 1244 can be reduced or released by reducing the distance between the first and second ends 1254 and 1256 of the tensioning line 1244 and the first and second projections 1264 and 1266 of the ram interlock 1226. This distance may be reduced by applying a distal force to proximal housing 708. When a distal force is applied to the proximal housing 708 while the distal housing 710 is held in place (e.g., by pressing the distal end 758 of the nose 716 of the distal housing 710 against the tissue of the patient), the proximal housing 708 and the float 1248 can move distally relative to the first and second tabs 1264, 1266 of the ram interlock 1226. When the tension on the first and seventh portions 1272 and 1284 of the tensioning line 1244 is reduced, the tension held by the third and fifth portions 1276 and 1280 of the tensioning line 1244 may be correspondingly reduced based on the winch equation described above. As a result, the distal force on the plunger 1110 of the ram 1102 due to the stored energy source 1202 may no longer be partially or fully opposed by the tensioning cord 1244 extending through the slot 1756 on the distal face 1754 of the plunger 1110, and the tensioning cord 1244 may slide around the first and second projections 1264, 1266 of the ram interlock 1226, which may allow the plunger 1110 to move distally into the syringe cavity 904, as described above and shown in fig. 12E. This, in turn, can urge the seal 910 distally to displace the contents of the reservoir 914 through the lumen 908 of the needle 906, as described above.

In some variations, the tensioning cord 1244 may begin to slide around the first and second projections 1264, 1266 of the ram interlock 1226 before the tension on the first and seventh portions 1272, 1284 of the tensioning cord 1244 is reduced to zero, which may allow the plunger 1110 to move distally into the syringe cavity 904. In this case, a portion of the force from compound spring 1218 may drive plunger 1110 distally within syringe cavity 904. If the user applies a distal force to the proximal housing 708 sufficient to reduce the pulling force on the first and seventh portions 1272, 1284 on the tensioning line 1244 to zero (e.g., by counteracting the full force from the locking spring 1246), the full force from the compound spring 1218 may urge the plunger 1110 to move distally within the syringe cavity 904. If the user applies a distal force to the proximal housing 708 beyond that required to reduce the tension on the first and seventh portions 1272, 1284 of the tensioning cord 1244 to zero, the additional distal force on the proximal housing 708 may be transferred to the additional force urging the plunger 1110 to move distally within the syringe cavity 904.

If the distal force on the proximal housing 708 is released, biasing the proximal housing 708 away from the ram interlock 1226 due to the locking spring 1246 (described above) may cause the proximal housing 708 to move distally away from the ram interlock 1226. The float 1248, in turn, can be moved distally away from the ram interlock 1226, which can restore tension in the first and seventh portions 1272, 1284 of the tensioning line 1244 and return the line tensioning system 1242 to a tensioned configuration. The rate control component 1204 may then prevent motion due to the stored energy source 1202. This may allow the user to selectively and reversibly start and stop the injection process or increase or decrease its speed. Fig. 22 shows a graph of the user force required to perform an injection using an injection device having a force assembly similar to force assembly 706 of injection device 700, illustrating the initial actuation force and the increased actuation force throughout the stroke of the injection process. The graph represents the force required to maintain a substantially constant distal movement of housing 708 (and thus plunger 1110) in order to maintain a substantially constant injection rate. As shown, the compound spring may relax during the injection stroke, thus exerting a decreasing force; thus, to maintain a substantially constant injection rate, the applied force may need to increase as the injection progresses (and thus increases as a function of time, as shown). It should be noted, however, that the user does not have to maintain a substantially constant injection rate. As shown, it is desirable to apply a force of about 4N in a particular configuration to sufficiently loosen the taut cord in order to allow the injection to begin, and then a lesser force may be required to continue the injection, although the resulting injection rate may be slower. It should be noted that this graph illustrates only the required user force for a similar device and is not meant to indicate that the injection device 700 may or must be in accordance with this representation.

In some variations, the injection device 700 may include an auto-complete mechanism as described with respect to the injection device 100. In some variations, the auto-complete mechanism may be based on the loosening of lock spring 1246. As described above, the locking spring 1246 may create a tension force on the tensioning line 1244. When the pulling force is released, the seal 910 may move distally to displace the contents of the reservoir 914 through the lumen 908 of the needle 906. Thus, injection can be automatically accomplished by reducing the tension on the tensioning cord 1244 due to the locking spring 1246. In some variations, the tension on the tensioning line 1244 due to the locking spring 1246 may be reduced by increasing the distance between the proximal and distal ends of the locking spring 1246. In some of these variations, this may be accomplished by positioning locking spring retainer 1250 within bore 1120 of ram 1102 such that the distal end of locking spring retainer 1250 is proximal to distal end 1124 of bore 1120 prior to auto-completion. Since the distal portion of locking spring 1246 may be received in locking spring collar 1250, the distal end of locking spring 1246 may thus be located proximal to distal end 1124 of inner bore 1120. When the activation is automatically completed, locking spring collar 1250 may move distally within inner bore 1120, which in turn may allow the distal end of locking spring 1246 to move distally within inner bore 1120, thereby releasing locking spring 1246. In some variations, the auto-completion may be initiated by ram interlock 1226. Locking spring collar 1250 may be held in place proximal to distal end 1124 of inner bore 1120 by two hook portions (not shown) on locking spring collar 1250 that extend outwardly into corresponding openings (not shown) of ram 1102. When the injection has been performed such that the ram 1102 has moved distally such that the openings in the inner bore 1120 are aligned with the inwardly facing proximal tabs 1298 of the flange 1296 of the ram interlock 1226, the tabs 1298 can enter the openings in the ram 1102 and can apply an inward force that pushes the hooks on the locking circlip 1250 apart such that they disengage from the openings in the ram 1102. When the hooks are disengaged from the openings, locking spring collar 1250 may move distally within inner bore 1120 to the distal end 1124 of the inner bore due to the biasing force from locking spring 1246. As described above, when locking spring retainer 1250 is moved distally, the distal end of locking spring 1246 may also be moved distally, which in turn may relax locking spring 1246 and may allow the injection to be automatically completed.

In some variations, one or more of the elements of the injection device 700 may optionally include a blocking feature to properly orient the elements relative to one another, as described above with respect to the injection device 100. Additionally or alternatively, in variations where the housing 702 has an elliptical cross-section, the elliptical cross-section may promote proper orientation of the housing elements.

In some variations, it may be desirable to assemble portions of the injection device 700 at a particular duration. For example, in some variations, the first portion of the injection device 700 may be assembled by attaching the tensioning cord 1244 to the float 1248 at its first and second ends 1254, 1256. The tensioning line 1244 can then be wrapped around the tether pile 1288 of the ram interlock 1226 — more specifically, the second portion 1274 and the sixth portion 1282 can be wrapped around the first and second tabs 1264, 1266, respectively, of the ram interlock 1226. Base stop cover 1126 may then be placed in alignment with ram interlock 1226. The ram 1102 can then be positioned such that the fourth portion 1278 of the cord engages the slot 1756 on the distal face 1754 of the plunger 1110 and the ram can be secured by lowering the base stop cap 1126 onto the ram interlock 1226. The composite springs 1218 may then be installed by inserting each composite spring 1218 proximally through the side lumen 1236 of the ram interlock 1226 and the side lumen 1138 of the base stop cap 1126 and attaching the proximal end of the composite spring 1218 to the ram crossbar 1112. The injection device 700 may then be assembled by attaching the nose 716 to the remainder of the distal housing 710, for example, using sonic welding. The compression spring 820 of the needle safety assembly 800 is then snapped into the nose 716 of the housing 710, and the lock assembly 826 may be snapped into the nose 716 via the lock assembly 826. The third part of the injection device 700 may be assembled by placing the syringe barrel 930 around the pre-filled syringe 704. The third portion can then be attached to the first portion of the injection device 700 by attaching the syringe sleeve 930 to the ram interlock 1226 via the latch 946 on the proximal lip 954 of the syringe sleeve 930. The attached first and third portions may then be inserted into a second portion of the injection device 700 (including the distal housing 710). The locking spring retainer 1250, the locking spring 1246 and the locking spring cover 1252 may then be inserted into the inner bore 1120 of the ram 1102. The proximal housing 702 can then be attached, which can be accomplished by snapping the float 1248 and proximal housing 708 together via a latch 1260 on the float 1248. In variations with the cover 772, a rigid needle shield 922 and cover 772 may also be installed. It should be appreciated that this assembly sequence is merely illustrative and that the various elements of the injection device 700 may be assembled in other sequences. It will also be appreciated that the assembly process may include other elements not included in the above description, and that not all elements described as assembled need be incorporated into the device.

Another embodiment of an injection device 1300 is shown in fig. 18, 19A-19D, including a housing 1302, a syringe 1304, and a power assembly 1306. The housing 1302 may be similar to the housing 102 described above with respect to the injection device 100 and may have the same components, configuration, and function. In some variations, the housing may optionally include a cover 1348, which may be similar to the cover 148 described above with respect to the injection device 100 and may have the same components and functions as described above.

Fig. 19A-19G show longitudinal cross-sectional views of the embodiment of the injection device of fig. 17 in various stages of use. Fig. 19A shows the device before use. Fig. 19B shows the device with the rigid needle shield and cap removed. Fig. 19C shows the device with the syringe in a partially extended position. Fig. 19D shows the device with the syringe in the fully extended position. Fig. 19E shows the device with the plunger portion moved toward a distal position within the syringe cavity. Fig. 19F shows the device with the syringe in a distal position within the syringe cavity. Fig. 19G shows the device with the needle shield extended. Similar to the injection device 100, the injection device 1300 may include a needle safety assembly 1400 that may be moved between a retracted position (shown in fig. 19A-19B) and an extended position (shown in fig. 19D-19G) as described in detail above with respect to the needle safety assembly 200. The needle safety assembly 1400 may have the same components, locations, and functions as the needle safety assembly 200 described with respect to the injection device 100.

The housing 1302 may also include an indicator, similar to the indicators described with respect to the injection device 100, that may indicate the progress or completion of an injection, as described in detail above, and may have an activated configuration and an inactivated configuration. In some variations of the injection device 1300, the dose tip indicator may include indicia. The flag may be spring biased and may be released by relative movement between the flag and the housing 1302. When the indicator is in the activated configuration, it may be viewed through the end cap 1318 of the proximal housing 1308.

The injector 1304 of the injection device 1300 may be similar to the injectors 104 and 704 described above with respect to the injection devices 100 and 700, and may have the same components, locations, and functions as described above.

The injection device 1300 may also include a syringe sleeve 1630. The syringe sleeve 1640 may be attached to the distal housing 1310 via a set of folds and tabs (not shown) that may retain the syringe sleeve 1630 relative to a ledge 1356 extending radially inward from the distal end 1314 of the distal housing 1310. The syringe 1304 may be slidably disposed within a syringe barrel 1630. The syringe sleeve 1630 may include a distal portion 1632 and a proximal portion 1634. The distal portion 1632 can be configured to slidably fit around the syringe body 1602. The proximal portion 1634 may have a larger diameter (or maximum distance transverse to the longitudinal axis) than the distal portion 1632. In some variations, the syringe barrel may comprise a transparent or translucent material, such as plastic. The proximal portion 1634 of the syringe sleeve 1630 may be configured to engage with a syringe cap 1836 (described below). The proximal portion 1634 of the syringe sleeve 1630 may include recesses, slots, or other grooves configured to mate with tabs on the distal end of latches on the syringe cap 1836 as described below.

As with the embodiments of injection devices 100 and 700, ram 1702 of injection device 1300 can be configured to transmit the distal force on proximal housing 1308 into different motions, depending on the stage of the injection process. In the first stage, the distal force on the proximal housing 1308 may be transferred into the distal movement of the syringe 1304 and force assembly 1306 relative to the distal housing 1310. In a second stage, distal forces on the proximal housing 1308 may be transferred to the contents of the reservoir 1614 of the syringe 1304 (e.g., a formulation containing a therapeutic agent) to be displaced through the lumen 1606 of the needle 1608.

In some variations, ram 1702 may be configured such that these effects of distal force on proximal housing 1308 may occur in the order described above. That is, the ram 1702 may be configured such that the distal force on the proximal housing 1308 may be first transferred into the distal movement of the syringe 1304 and force assembly 1306 relative to the distal housing 1310, and then second transferred into the displacement of the contents of the reservoir 1614 of the syringe 1304 (e.g., a formulation containing a therapeutic agent) through the lumen 1608 of the needle 1606. This may be desirable, for example, because it may allow the syringe 1304 to be moved distally so that the needle 1606 may pierce the patient's tissue before the contents of the syringe cavity 1604 of the syringe 1304 are displaced through the lumen 1608 of the needle 1606.

In some variations, the sequence of application of the distal force on the proximal housing 1308 may be attributable to different amounts of force required for each movement. For example, when the force on the proximal housing 1308 is above a first threshold (e.g., above about 1N, above about 2N, above about 3N, above about 4N, above about 5N, above about 6N, above about 7N, or higher), the ram 1702 can transmit a distal force on the proximal housing 1308 into the distal motion of the syringe 1304 and force assembly 1306 relative to the distal housing 1310; and when the force on the proximal housing 1308 is above a second, higher threshold (e.g., above about 5N, above about 10N, above about 15N, above about 20N, above about 25N, or higher), the ram 1702 may transfer the distal force on the proximal housing 1308 into displacement of the contents of the reservoir 1614 of the syringe 1304 through the needle 1606. In some variations, each threshold may be attributed to a proximal force caused by friction on the syringe 1304 and ram 1702, respectively. It should be appreciated that in other variations, ram 1702 may transfer the distal force on proximal housing 1308 into different motions in different orders and through different mechanisms. For example, in some variations, the application of the distal force may be selected by a mechanism for manual selection by a user. It should also be appreciated that ram 1702 may transfer the distal force on proximal housing 1308 into more or less motion.

The ram 1702 may include a plunger 1710. Plunger 1710 can be configured to slide through a lumen 1842 of a syringe cap 1836 (described below) and can be configured to slide within a syringe cavity 1604 of syringe 1304. The distal end 1716 of the plunger 1710 may be configured to engage the seal 1610 of the syringe 1304. If plunger 1710 moves distally relative to and within syringe cavity 1604, plunger 1710 can push seal 1610 distally relative to and within syringe cavity 1604. This movement of the seal 1610 may reduce the volume of the reservoir 1614 containing the formulation containing the therapeutic or diagnostic agent. Thus, distal movement of the plunger 1710 and thus the seal 1610 relative to and within the syringe cavity 1604 may displace the contents of the reservoir 1614 through the lumen 1608 of the needle 1606. Plunger 1710 may include an inner tube 1742 coaxially within an outer tube 1744. The inner tube 1742 and the outer tube 1744 may form an inner lumen 1746 within the inner tube 1742 and an outer annular lumen 1748 between the inner tube 1742 and the outer tube 1744. In some variations, the outer annular inner cavity may be divided into two or more (e.g., three, four, etc.) radial segments. The inner cavity 1746 and the outer annular cavity 1748 may cooperate with the force assembly 1306 to direct pressure flow from the stored energy source 1802 as described in detail below.

Application of a distal force on the proximal housing 1308 may cause the proximal housing 1308 to move distally. If the distal housing 1310 is held in place (e.g., by pressing the distal end 1358 of the nose 1316 of the distal housing 1310 against the patient's tissue), the proximal housing 1308 can move distally relative to the distal housing 1310. Movement of the proximal housing 1308 can be transmitted via a power assembly 1306 (discussed in more detail below) to slide the power assembly 1306 and syringe 1304 distally relative to the distal housing 1310 from a retracted position (shown in fig. 19A-19B) if the distal force on the proximal housing 1308 is above a requisite force threshold. The threshold force required may be attributed to friction between the outer surface of the syringe body 1602 and the inner surface of the syringe sleeve 1630. In some variations, this friction may additionally or alternatively be created between the syringe body 1602 and the inner surface of the syringe sleeve 1630 by a seal attached to the inner surface of the syringe sleeve 1630. When the threshold distal force is reached, the force assembly 1306 and syringe 1304 may move distally toward the nose 1316 of the distal housing 1310, such that the syringe 1304 may move toward the extended position (described above with respect to the syringe 104 of the injection device 100), as shown in fig. 19C.

As the distal tip 1624 of the needle 1606 approaches the distal opening 1312 of the nose 1316, the sheath of the needle safety assembly 1400 may be unlocked from the retracted position as described in detail above with respect to the injection device 100. As the distal tip 1624 of the needle 1606 moves to extend beyond the distal end 1358 of the nose 1316, the needle 1606 can pierce tissue pressed against the distal end 1358 of the nose 1316. The syringe 1304 may continue to move distally relative to the syringe sleeve 1630 until the syringe 1304 has reached the extended position, as shown in fig. 19D. In the extended position, the distal tip 1624 of the needle 1606 may have reached a desired depth (described above). In some variations, when the syringe 1304 reaches the extended position, further distal movement relative to the distal housing 1310 may be prevented by a proximal lip 1652 extending radially outward from the proximal end 1650 of the syringe body 1602, the proximal lip 1652 may be configured such that it may fit within the proximal portion 1634 of the syringe sleeve 1630 but may not enter the distal portion 1632 of the syringe sleeve 1630. Once the injector 1304 reaches the extended position, the syringe manifold 1866 (described below) may also engage the pressure chambers 1824 via a bend 1868 on the syringe manifold 1866.

It should be noted that due to the relative amount of force required to move the force assembly 1306 and syringe 1304 relative to the distal housing 1310 and move the syringe 1710 distally within the syringe cavity 1604, the force assembly 1306 and syringe 1304 may be moved distally together with the distal force on the proximal housing 1308 rather than the force assembly 1306 acting on the syringe 1304 (e.g., to move the plunger 1710 distally within the syringe cavity 1604 to act on the seal 1610 and displace the contents of the reservoir 1614). More specifically, the amount of force required to overcome the friction between the outer surface of the syringe body 1602 of the syringe 1304 and the inner surface of the syringe sleeve 1630 may be less than the amount of force required to move the plunger 1710 distally within the syringe cavity 1604 as described in detail below.

If the distal force on the proximal housing 1308 is released while the force assembly 1306 and syringe 1304 are moved from the retracted position to the extended position, the force assembly 1306 and syringe 1304 may remain in place in an intermediate position relative to the syringe barrel 1630.

After the force assembly 1306 and syringe 1304 have been moved distally relative to the distal housing 1310 such that 1304 is in the extended configuration and the distal tip 1624 of the needle 1606 is at the desired depth, if additional distal force on the proximal housing 1308 is above the necessary force threshold, this force may be transferred into the distal motion of the ram 1702 relative to the syringe cavity 1604. Above the requisite force threshold, the plunger 1710 and seal 1610 may begin to move distally relative to and within the syringe cavity 1604, as shown in fig. 19E, which may reduce the volume of the reservoir 1614 and displace the contents of the syringe cavity 1604 through the lumen 1608 of the needle 1606, as described above with respect to the injection device 100. The threshold force required to move syringe 1710 and seal 1610 distally within syringe cavity 1604 may be due first to ridge 1670 extending radially inward from inner surface 1612 of syringe cavity 1604. The ridge 1670 may be located distal to the seal 1610 before the seal 1610 has moved within the syringe cavity 1604. When sufficient distal force is applied to the proximal housing 1308 to deflect the seal 1610 distally over the ridge 1670, the seal 1610 can then move further distally within the syringe cavity 1604 if the force is sufficient to overcome the friction between the seal 1610 and the plunger 1710 and the inner surface 1612 of the syringe body 1602 and between the plunger 1710 and the syringe cap 1836. The additional force to move the plunger 1710 and seal 1610 distally relative to and within the syringe cavity 1604 may also be attributable to the force assembly 1306 described below.

As described above with respect to the force assembly 106 of the injection device 100, the force assembly can provide an injection force sufficient (alone or in addition to the injection force supplied by the user) to inject a particular formulation of a particular volume through a particular sized needle at a particular time, as described in detail with respect to the force assembly 106. Similar to the force assembly 106, the force assembly 1306 may include a stored energy source and a rate control assembly. As in the power assembly 106 described with respect to the injection device 100, the power assembly 1306 may include a stored energy source 1802 that may be configured to provide a force to displace contents of the reservoir 1614 of the syringe 1304 through the lumen 1608 of the needle 1606, and a rate control assembly 1804 that may include a braking assembly that may limit or inhibit the stored energy source 1802 from causing the contents of the reservoir 1614 of the syringe 1304 to be displaced through the lumen 1606 of the needle 1608. In the illustrated embodiment of the injection device 1300, the stored energy source 1820 may comprise a compressed gas or liquid propellant in a supercritical state. The compressed gas or liquid propellant may be held within a container, such as a syringe 1806 (e.g., a double-crimped metal syringe), which may be located at the proximal end 1320 of the proximal housing 1308. The syringe 1806 may be fixedly attached to the end cap 1318 of the proximal housing 1308 such that distal movement of the proximal housing 1308 may cause distal movement of the syringe 1806. In some variations, barrel 1806 may be attached to end cap 1318 of proximal housing 1308 by a set of folds that may snap over barrel 1806 to retain it extending distally from the inside of end cap 1318.

The compressed gas or liquid propellant may comprise any gas suitable for compression. In some variations, the compressed gas or liquid propellant may include a gas in a gaseous state at high pressure (e.g., N)₂Ar or compressed air). In these variations, when compressed gas is released from the syringe 1806, the output pressure may decrease as the compressed gas exits the syringe 1806. In other variations, the liquid propellant may comprise a gas that is a saturated liquid at high pressure (e.g., CO)₂And R134A (also known as HF134A or HFC-R134 a)). In these variations, the output pressure may be constant as liquid propellant is released from the syringe 1806, so long as a portion of the propellant remains in liquid form in the syringe 1806. The compressed gas or liquid propellant may have any suitable saturation pressure.

When a compressed gas or liquid propellant in a supercritical state is released from the syringe 1806 via valve 1808 (described below), it may cause the seal 1610 of the syringe 1304 to move distally relative to and within the syringe cavity 1604, which may displace the contents of the reservoir 1614 through the needle 1606 of the syringe 1304. In some variations, the force from the compressed gas or liquid propellant may act directly on all or a portion of the proximal side of the seal. In other variations, the force from the compressed gas or liquid propellant may act indirectly on the seal; that is, the force may act on a surface outside of the seal, which in turn may cause distal movement of the seal. In still other variations, the force from the compressed gas or liquid propellant may act on the seal both directly and indirectly. In each of these variations, the force from the compressed gas or liquid propellant may act on different sized surface areas (i.e., surface areas orthogonal to the longitudinal axis). In some variations, the force may act on a surface having a cross-sectional area approximately equal to the cross-sectional area of the syringe cavity, for example, by acting directly on the seal. In other variations, the force may act on a surface area having a smaller cross-sectional area than the syringe cavity, for example by acting on a portion of the seal or an annular surface area having a smaller cross-sectional area than the syringe cavity located radially outward of the syringe cavity. In still other variations, the force from the compressed gas or liquid propellant may act on a surface area of greater cross-sectional area than the syringe cavity, for example by acting on the seal and an annular surface area located radially outward of the syringe cavity or by acting on an annular surface area located radially outward of the syringe cavity having a cross-sectional area greater than the syringe cavity. One portion of the flow path (e.g., the proximal portion) may have the same or a different cross-sectional (i.e., orthogonal to the longitudinal axis) profile as a second portion of the flow path (e.g., the distal portion). In some variations, the flow path of the compressed gas or liquid propellant may be linear, while in other variations, the flow path may be non-linear. For example, there may not be a straight flow path between two locations (e.g., a proximal-most location and a distal-most location) in the flow path of the compressed gas or liquid propellant, or the flow path of the compressed gas or liquid propellant may have two or more sections that are not parallel to each other.

In variations where the force may act on a larger surface area, this may allow the compressed gas or liquid propellant to create more pressure to move the seal distally. The saturation pressure of the compressed gas or liquid propellant and the cross-sectional area over which this pressure can act can thus be selected one after the other to deliver the appropriate force based on the formulation viscosity, needle selection, injection volume and injection time required. In some variations, for example, the force assembly can inject 1.9mL of 39cP solution through a 27ga needle within 10 seconds by applying a force of about 52-54N. For example, in some variations, the injection device 1300 may use a liquid propellant (e.g., CO) having a saturation pressure of about 850PSIa acting on a cross-sectional area of 0.014 square inches₂) It can supply a force of about 52N. In other variations, the injection device 1300 may use a liquid propellant (e.g., R134A) having a saturation pressure of about 85PSIa acting on a cross-sectional area of about 0.138 square inches. In other variationsIn one version, the injection device 1300 may use a compressed gas (e.g., N) having a typical pressure of about 2700PSIa acting over a cross-sectional area of about 0.0043 square inches₂). In other variations, the injection device 1300 may use a compressed gas (e.g., Ar) having a typical pressure of about 1750PSIa acting on a cross-sectional area of about 0.0067 square inches. It should be understood that these pressures, surfaces, and forces are merely illustrative examples; any suitable combination may be selected to achieve the desired injection force.

As shown in fig. 19A-19G and by arrows in fig. 20A, the stored energy source 1802 can include a flow directing assembly for directing compressed gas or liquid propellant when released. The flow directing assembly may direct compressed gas or liquid propellant distally through the lumen 1746 of the plunger 1710, radially outward through the reoriented opening, and into a pressurization region 1812 formed distally of the syringe cap 1836. More specifically, as described above, the plunger of the ram 1702 may include an inner tube 1742 coaxially located within an outer tube 1744. The inner tube 1772 and the outer tube 1744 can form an inner cavity 1746 within the inner tube 1772 and an outer annular cavity 1748 between the inner tube 1772 and the outer tube 1744. The proximal opening 1750 of the lumen 1746 may be connected with the proximal opening 1814 of the valve 1808. The distal openings 1752 of the lumen 1746 may be in fluid communication with the inflow openings 1818 of the manifold 1816. The inflow opening 1818 of the manifold 1816 may be in fluid communication with one or more outflow openings 1820 of the manifold 1816. In some variations, the manifold 1816 may have four outflow openings 1820 connected with the inflow openings 1818, and the outflow openings 1820 may be positioned axially away from the longitudinal direction of the manifold 1816 such that the outflow openings 1820 are oriented outside of the syringe body 1602. The outflow opening 1820 of the manifold 1816 may be in fluid communication with the pressurized region 1812.

As shown in fig. 20A and in more detail in fig. 20B, the pressurization region 1812 can be formed within a pressure chamber 1824 located distally of the syringe cap 1836 and around the syringe body 1602. The pressure chamber 1824 may include a cylinder 1826 having an inner cavity 1828 between a proximal end 1830 and a distal end 1832. Proximal end 1830 of pressure chamber 1824 may engage syringe manifold 1866 via bend 1868 when syringe 1304 is in the extended position as described above. The distal end 1832 of the pressure chamber 1824 may form a seal 1834 around the proximal portion 1634 of the syringe sleeve 1630 such that the proximal portion 1634 of the syringe sleeve 1630 may be located within the lumen 1828 of the pressure chamber 1824. The syringe sleeve 1630 may slide within the seal 1834. The syringe cap 1836 may further include a body 1838, which may be slidably disposed within the pressure chamber 1824. The syringe cover 1836 may form a seal 1840 with the inner surface of the cylinder 1826 of the pressure chamber 1824 sufficient to prevent pressurized gas from traveling between the syringe cover 1836 and the inner surface of the cylinder 1826 of the pressure chamber 1824 past the seal 1840. The syringe cap 1836 may also have a lumen 1842 therethrough, which may be configured to allow the plunger 1810 of the ram 1702 to move therethrough. There may also be a seal 1844 between the surface of the syringe cap 1836 forming the lumen 1842 and the plunger 1710 sufficient to prevent pressurized gas from traveling between the syringe cap 1836 and the plunger 1710 past the seal 1844. One or more latches 1846 may extend distally from the body 1838 of the syringe cap 1836. Each latch 1846 may include an elongated portion 1848 having a proximal portion attached to the body 1838 of the syringe cap 1836 and a tab 1850 at a distal end of the elongated portion 1848. The tabs 1850 may be configured to fit in recesses, slots, or other grooves (e.g., recesses 1674) in the proximal portion 1634 of the syringe sleeve 1630 described above. When the latch 1846 is engaged with the syringe barrel 1630, the position of the syringe cap 1838 may be fixed relative to the position of the syringe barrel 1630.

The seal 1834 between the pressure chamber 1824 and the proximal portion 1634 of the syringe sleeve 1630, the seal 1840 between the syringe cap 1836 and the pressure chamber 1824, and the seal 1844 between the syringe cap 1836 and the plunger 1710 may thus form a volume-altering pressurized region 1812. The volume of the pressurized region 1812 may be minimized when the proximal portion 1634 of the syringe sleeve 1630 is adjacent the distal end 1832 of the pressure chamber 1824 as shown in fig. 20A. As the compressed gas or liquid propellant flows into the pressurized region 1812, the pressure from the compressed gas or liquid propellant may drive the distal end 1832 of the pressure chamber 1824 distally relative to the syringe sleeve 1630 so as to increase the volume of the pressurized region 1812. The volume of the pressurization region 1812 may be greatest when the pressure chamber 1824 has been moved fully distally such that the distal end 1832 of the pressure chamber 1824 may be adjacent the distal end 1314 of the distal housing 1310 as shown in fig. 19F.

When the pressure chamber 1824 is urged distally relative to the syringe sleeve 1630, this in turn may urge the plunger 1710 distally relative to the syringe cavity 1604. When plunger 1710 slides distally relative to and within syringe cavity 1604, this in turn can push seal 1610 distally relative to syringe cavity 1604, which in turn reduces the volume of reservoir 1614 of syringe 1304. This may displace the contents of the reservoir 1614 through the lumen 1608 of the needle 1606 of the syringe 1304 as described above.

As shown by the arrows in fig. 20C, the injection device 1300 can also include a vent path for atmospheric gas in a region 1682 leading to the syringe cavity 1604 proximate the seal 1610. This can limit the creation of negative pressure in region 1682 as seal 1610 moves distally relative to and within syringe cavity 1604. In those variations where direct pressurization of seal 1610 is not contemplated. It may be desirable to limit the negative pressure created in the area 1682 to avoid an unpleasant force profile experience by the user while the injection is in progress, and/or it may be desirable to create this negative pressure to limit the risk that any leakage from the pressurized area 1812 may result in direct pressurization of the seal 1610, which in turn increases the risk of leakage into the reservoir 1614. In some variations, the vent passage may be formed by further vent openings in the manifold 1816. The manifold 1816 may include one or more inflow vent openings 1862 in fluid communication with the region of the injector cavity 1604 proximate the seal 1610 and one or more outflow vent openings 1864 in fluid communication with ambient pressure in the housing 1302 via an outer annular inner cavity 1748 of the plunger 1710.

However, the plunger 1710 moving distally to press against the seal 1610 of the syringe 1304 may sometimes be prevented or limited by the rate control assembly 1804. In some variations, the rate control assembly 1804 may include a valve 1808 and a syringe manifold 1866 as shown in fig. 19A-19G. When the valve 1808 is in the closed configuration, the valve 1808 may limit the ability of the compressed gas or liquid propellant to exit the syringe 1806, and thus the compressed gas or liquid propellant may not act on the pressure chamber 1824 to move the pressure chamber 1824 distally, and thus may not provide the force to move the plunger 1710 and seal 1610 distally within the syringe cavity 1604 of the syringe 1304 as described above. When the valve 1808 is in the open configuration, compressed gas or liquid propellant may exit the barrel 1806 and act distally on the pressure chamber 1824, and thus may provide a force to move the plunger 1710 and seal 1610 distally within the syringe cavity 1604 to displace the contents of the reservoir 1614 through the lumen 1608 of the needle 1606. In some variations, the valve 1808 may also have an intermediate configuration, wherein the valve 1808 partially restricts the flow of compressed gas or gas propellant, but need not have such an intermediate configuration. Syringe manifold 1866 may form a seal between valve 1808 and pressure chamber 1824. The syringe manifold 1866 may comprise any suitable material, such as, but not limited to, a compliant material, for example, an overmolded plastic of a thermoplastic elastomer.

In some variations, the valve 1808 may be biased toward the closed configuration. Valve 1808 may be moved to the open configuration by application of a distal force on valve 1808 by syringe 1806. The distal force may be applied by applying the distal force to the proximal housing 1308. When a distal force is applied to the proximal housing 1308 while the distal housing 1310 is held in place (e.g., by pressing the distal end 1358 of the nose 1316 of the distal housing 1310 against the patient's tissue), the proximal housing 1308 and syringe 1806 may move distally relative to the distal housing 1310 and relative to the pressure chamber 1824 and syringe manifold 1866. This may cause valve 1808 to press against syringe manifold 1866, which may cause valve 1808 to open. As a result, valve 1808 may open, thereby releasing pressurized gas from syringe 1806 into pressurization region 1812 via valve 1808, syringe manifold 1866, interior cavity 1746 of plunger 1710, and manifold 1816, as described above. This may increase the volume of the pressurization region 1812, which may drive the plunger 1710 and seal 1610 distally into the syringe cavity 1604 of the syringe 1304 as described above to displace the contents of the reservoir 1614 through the lumen 1608 of the needle 1606. Fig. 23 shows an illustrative force graph for an injection device having a force assembly similar to force assembly 1306 of injection device 1300. The graph shows the amount of user force required to displace a simulated fluid having a range of viscosities with and without a syringe installed in the injection device, with the seal displacing the contents of the reservoir at a rate of about 6 mm/s. As can be seen, the force required with the syringe installed is approximately the same for all three simulated viscosities-a force from the user of about 15N to 18N is approximately the valve actuation force, while a significantly higher force is required without the syringe installed. Thus, the graph represents the force that can be generated by the force applicator assembly in order to achieve the desired injection force. It should be noted that this graph only illustrates the forces of similar devices and is not meant to indicate that the injection device 700 may or must be consistent with this representation.

If the distal force on proximal housing 1308 is released, the biasing of valve 1808 toward the closed configuration may cause valve 1808 to close, thereby stopping or reducing the flow of pressurized gas into pressurized region 1812. When the flow of pressurized gas into the pressurized region 1812 ceases, the pressure already in the pressurized region 1812 may continue to displace the pressure chamber 1824 distally relative to the syringe sleeve 1630 until the pressure in the pressurized region 1812 drops to the same level as ambient pressure. After this initial glide period, displacement of the contents of reservoir 614 through needle 1606 may cease. This may allow the user to selectively and reversibly start and stop the injection process. In some variations, the power assembly 1306 may include a mechanism to stop the injection process without allowing a coast period. In some such variations, such a mechanism may decompress the compression region 1812 when the distal force on the proximal housing 1308 is released. For example, the seal between the valve 1808 and the syringe manifold 1866 may be configured to leak when the distal force on the proximal housing 1308 is released.

It should be appreciated that in some variations, the rate control assembly 1804 may include different types of valves or additional elements. For example, in variations of injection devices that use compressed gas or liquid propellant having a high pressure, the valve may include a piercing mechanism and/or a pressure regulator, but need not be. A puncturing mechanism, such as but not limited to a spring loaded pin with a grenade pin type release mechanism, or a spring loaded gas cylinder with a stationary pin, may release higher pressure gas. A pressure regulator, such as but not limited to a diaphragm regulator that uses a spring to adjust the force on a poppet valve, may drop the gas to a safe and usable pressure.

In some variations, the injection device 1300 may include an auto-complete mechanism. In some variations, the auto-complete mechanism may allow the valve 1808 to be locked in an open configuration. When the valve is locked in the open configuration, the force from the compressed gas or liquid propellant may move the seal distally until the injection is complete and all of the contents of the reservoir have been displaced. In these variations, the injection device may further comprise a pressure relief port that allows pressure to be released once all of the contents of the reservoir have been displaced, to prevent pressure buildup after the injection is completed.

In some variations, one or more of the elements of the injection device 1300 may optionally include a blocking feature to properly orient the elements relative to each other, as described above with respect to the injection device 100.

Another embodiment of an injection device 2600 is shown in fig. 26 and 27A-27H. Fig. 26 is a perspective view of the injection device 2600, and fig. 27A-27H illustrate longitudinal cross-sectional views of the embodiment of the injection device 2600 of fig. 26 in various stages of use. As shown therein, the injection device 2600 may include a housing 2602, a syringe 2604, and a power assembly 2606. The housing 2602 may be similar to the housing 102 described above with respect to the injection device 100 and may have the same components, configurations, and functions. In some variations, the housing may optionally include a cap, which may be similar to cap 148 described above with respect to injection device 100, and may have the same components and functions as described above.

The syringe 2604 of the injection device 2600 may be similar to the syringe 104 described above with respect to the injection device 100, and may have the same components, positions, and functions as described above.

In general, the injection device 2600 may be initially in a state with the needle safety assembly 2622 extending from the distal end of the housing 2602 such that the syringe is fully contained within the housing 2602 and the needle safety assembly 2622 without any exposure of the needle 2628 of the syringe 2604, as shown in fig. 27A. In variations that include a cap, the cap may be removed from the injection device 2600 prior to use. The distal end of the injection device 2622 may then be pressed against the tissue of the patient. Proximal force from the patient's tissue (e.g., due to a user (patient or another person) holding the housing 2602 and pressing the injection device 2600 against the tissue) may overcome the bias of the needle safety assembly toward the extended position, thereby moving the needle safety assembly 2622 from the extended position to the retracted position, as shown in fig. 27B (partially retracted) and 27C (fully retracted). Retraction of the needle safety assembly 2622 may expose the needle 2628 of the syringe 2604, allowing the needle 2628 to pierce the tissue of the patient. Retraction of the needle safety assembly 2622 may release a locking mechanism including an interlocking ring 2634, which prevents distal movement of the plunger 2614 within the syringe 2604 prior to retraction of the needle safety assembly 2622. Once the locking mechanism is released as shown in fig. 27C, application of a distal force by a user on the proximal housing may cause plunger 2614 to move distally to contact seal 2612 of syringe 2604, as shown in fig. 27D, and may then cause both plunger 2614 and seal 2612 to move distally within syringe cavity 2616. This, in turn, may cause the contents of reservoir 2630 of syringe 2604 to be delivered to the patient via needle 2628. During an injection procedure, the injection force applied by the user may be amplified by the stored energy source while still allowing the user to selectively start and stop the injection procedure as desired. Energy storage spring 2652 may be configured to press plunger 2614 distally within syringe cavity 2616, but energy storage spring 2652 may be prevented from acting on plunger 2614 by friction generated by brake pad 2658 when a user is not applying force. This force may reduce or eliminate the friction generated by the brake pad 2658 when the user applies force to the injection device, thereby allowing the stored energy spring 2652 to act on the plunger. Once the plunger 2614 and seal 2612 have been depressed such that all or nearly all of the dose has been delivered to the patient, the metering may be automatically completed and/or the metering tip indicator may be enabled. Fig. 27F shows the device with the plunger 2614 and seal 2612 nearly in the final distal position within the syringe cavity, with the metering tip indicator 2618 in the activated configuration. Fig. 27G shows the device with the plunger 2614 and seal 2612 in the final distal position within the syringe cavity. After the dose is complete, if the injection device 2600 is removed from the patient, the needle safety assembly 2622 may be returned to the extended position as shown in fig. 27H, where the locking ring 2668 may prevent the needle safety assembly 2622 from being withdrawn again.

Thus, as shown in the above description, the distal force on the proximal housing 2624 may be transferred into different motions depending on the stage of the injection process. In a first stage, if the needle shield 2620 of the needle safety assembly 2622 is held in place (e.g., by pressing the distal end of the shield 2620 against the tissue of the patient), a distal force on the proximal housing 2624 may be transferred into the distal movement of the injection device 2600 relative to the needle safety assembly 2622. In a second stage, distal forces on the proximal housing 2624 may transfer the contents of the reservoir 2630 of the syringe 2604 (e.g., a formulation containing a therapeutic agent) through the lumen of the needle 2628.

In some variations, the ram 2610 may be configured such that these effects of distal forces on the proximal housing 2624 may occur in the order described above. That is, the ram 2610 may be configured such that a distal force on the proximal housing 2624 may be transmitted first into the distal movement of the injection device 2600 relative to the needle safety assembly 622, and then second into the displacement of the contents of the reservoir 2630 of the syringe 2604 (e.g., a formulation containing a therapeutic agent) through the lumen of the needle 2628. This may be desirable, for example, because it may allow the syringe 2604 to move distally so that the needle 2628 may pierce the patient's tissue before the contents of the syringe cavity 2616 of the syringe 2604 are displaced through the lumen of the needle 2628.

In some variations, the sequence of application of the distal force on the proximal housing 2624 may be due to the different amounts of force required for each movement. For example, when the force on the proximal housing 2624 is above a first threshold (e.g., above about 1N, above about 2N, above about 3N, above about 4N, above about 5N, above about 6N, above about 7N, or higher), the ram 2610 may transfer a distal force on the proximal housing 2624 into distal movement of the remainder of the injection device 2600 relative to the needle safety assembly 2622; and when the force on the proximal housing 2624 is above a second, higher threshold (e.g., above about 5N, above about 10N, above about 15N, above about 20N, above about 25N, or higher), the ram 2610 may transfer the distal force on the proximal housing 2624 into the displacement of the contents of the reservoir 2630 of the syringe 2604 through the needle 2628. It should be appreciated that in other variations, ram 2610 may transfer the distal force on proximal housing 2624 into different motions in different orders and through different mechanisms. For example, in some variations, the application of the distal force may be selected by a mechanism for manual selection by a user. It should also be appreciated that the ram 2610 may transfer the distal force on the proximal housing 2624 into more or less motion.

As briefly described above, in some configurations, application of a distal force on the proximal housing 2624 may cause distal movement of the injection device 2600 relative to the needle safety assembly 2622. In an initial configuration prior to use, as shown in fig. 27A, if the shield 2620 of the needle safety assembly 2622 is held in place (e.g., by pressing the distal end of the shield 2620 against tissue of a patient), the proximal housing 2624, the distal housing 2632, the power assembly 2606 (described in more detail below), and the syringe 2604 may slide distally relative to the needle safety assembly 2622. In effect, this may cause needle safety assembly 2622 to eventually move from an extended position (as shown in fig. 27A) through a partially retracted position (as shown in fig. 27B) to a fully retracted position (as shown in fig. 27C) in which the distal end of shield 2620 is flush with the distal end of distal housing 2632. When the needle safety assembly 2622 is retracted, the distal tip of the needle 2628 may move beyond the distal end of the shield 2620 and the needle 2628 may pierce tissue pressed against the distal end of the shield 2620. When the needle safety assembly 2622 is complete, the distal end of the needle 2628 may have reached the desired depth (described above), and the distal end of the distal condenser housing 2632 pressing against the tissue may prevent further distal movement of the needle 2628.

The force required to cause retraction of the needle safety assembly 2622 may be determined by a biasing element that may bias the needle safety assembly 2622 toward the extended position. For example, as shown in fig. 27A-27H, the biasing element may comprise a compression spring 2622. The compression spring 2662 may have a proximal end fixed relative to the housing 2602 and a distal end fixed relative to the needle safety assembly 2622, biasing the shield 2620 distally relative to the housing 2602. When needle safety assembly 2622 is in the extended position, compression spring 2662 may be in the extended position, as shown in fig. 27A. As needle safety assembly 2622 moves toward the fully retracted position, it may compress, as shown in fig. 27B-27C. The needle safety assembly 2622 may remain in a fully retracted position throughout the injection, as shown in fig. 27D-27G, until the proximal force on the shield 2620 is removed (e.g., the distal end of the injection device 2600 is removed from the patient's tissue), as described in more detail below.

Before the needle safety assembly 26222 is fully retracted, the start of an injection may be limited by a locking mechanism (e.g., via distal movement of the plunger 2614 within the syringe cavity 2616). In some variations, the locking structure may include an interlocking ring 2634. The ram housing 2636 can include one or more bends 2638 configured to constrain distal movement of the ram 2610 relative to the syringe 2604. As shown in fig. 30, the plunger 2614 (described in more detail below) may include a groove 2640 at its distal end that may extend circumferentially around a middle portion of a widened region 2642 at the distal end of the plunger 2614. The wedge portion of the bent portion 2638 of the hammer case 2636 may be fitted in the groove 2640 in the initial locking state, as shown in fig. 27A. When the wedge-shaped portions of the bent portions 2638 engage the grooves 2640, they may limit distal movement of the ram 2610. To move the ram 2610 distally, the bent portion 2638 can be bent outward. Interlocking ring 2634 may include an annular structure (shown isolated in fig. 29B) shaped and sized to fit around ram housing 2636 and within proximal housing 2624 and/or distal housing 2632. When the interlocking ring 2634 is in its locked position (as shown in fig. 27A), it may be located around the bent portion 2638 of the ram housing 2636, which in turn may serve as a ferrule for inhibiting outward bending of the bent portion 2638. The bend 2638 may be allowed to bend outward by the interlocking ring 2634 being displaced such that it no longer lies around the bend 2628 and thus no longer constrains it. Fig. 27C shows this unlocked configuration. As shown therein, the bent portion 2638 may have room to bend outward when the interlocking ring 2634 is in the proximal unlocked position. Although the embodiment of the injection device 2600 includes three bends 2638, it should be appreciated that in other variations, the injection device 2600 may include fewer (e.g., one or two) or more (e.g., four, five, six, or more) bends.

Release of the locking mechanism may be coupled with retraction of the needle safety assembly 2622. That is, the locking structure may limit distal movement of the plunger 2614 (described in more detail below) until the needle safety assembly 2622 is fully retracted, and thus until the needle 2628 is at its desired depth. In some variations, retraction of needle safety assembly 2622 may cause proximal displacement of interlocking ring 2634. For example, needle safety assembly 2622 may include a proximal portion configured to engage interlocking ring 2634. In the injection device 2600, a proximal portion of the needle safety assembly 2622 may include one or more arms 2644. When arm 2644 is in the proximal position (i.e., when needle safety assembly 2622 is retracted), arm 2644 may engage with interlocking ring 2634. In fig. 27B, the proximal ends of arms 2644 can be seen engaged with interlocking ring 2634. In fig. 27C, the proximal end of the arm 2644 has pressed against the distal side of the interlocking ring 2634, moving it proximally relative to the ram housing 2634 into an unlocked configuration.

A perspective view of needle safety assembly 2622 is shown in fig. 29A. While shown as having three arms 2644, it should be appreciated that needle safety assembly 2622 may have fewer (e.g., zero, one, or two) arms or more (e.g., four, five, or six) arms. Fig. 28A illustrates a cut-away perspective view of the distal end of the injection device 2600 showing the needle safety assembly 2622 in a first configuration in an initial extended position at the cover 2620. Fig. 28B shows the same view in a second configuration, with the cover 2620 in a retracted position. As can be seen in these figures, as the shield 2620 moves from the extended position to the retracted position, the needle safety assembly 2622 (including the arms 2644) moves proximally relative to the distal housing 2632 so that it can contact the interlock ring 2634. A perspective view of the interlocking ring 2634 is shown in fig. 29B. As shown therein, in some variations, interlocking ring 2634 may include one or more tabs 2646 (e.g., three tabs as shown therein) on a distal surface that may correspond with arms 2644 on needle safety assembly 2622 and may be configured to engage with arms 2644.

After the needle safety assembly 2622 is retracted and thus the interlocking ring 2634 is displaced into the unlocked configuration as shown in fig. 27C, additional distal force on the proximal housing 2624 may be transferred into the distal movement of the ram 2610. Ram 2610 may include a rod 2648 and a plunger 2614. The rod 2648 may be fixedly attached on its proximal end to the end cap 2650 of the proximal housing 2624 and thus may transfer a distal force on the proximal housing 2624 into a distal force on the ram 2610. The ram 2610 may also include a plunger 2614. All or a proximal portion of the plunger 2614 may be hollow, and a distal end of the rod 2648 may extend through an open proximal end of the hollow plunger 2614. The rod 2648 can slide within a limited range of motion within the proximal portion of the plunger 2614. This range of motion may be defined by a variable gap between the end cap 2650 and the proximal end 2676 of the plunger 2614, thereby allowing the rod 2648 (which is fixedly attached to the end cap 2650) to slide distally within the plunger 2614 until the interior of the end cap 2650 (e.g., a protruding tubular boss that contacts the end cap) contacts the proximal end 2676 of the plunger 2614. This range of motion may facilitate variable application of braking force as described in more detail below.

Plunger 2614 may be configured to slide within syringe cavity 2616 of syringe 2604. The distal end of plunger 2614 may be configured to engage with seal 2612 of syringe 2604. Initially, a distal force on the proximal housing 2624 may move the ram 2610 distally, thereby deflecting the bent portion 2638 of the ram housing 2636 radially outward until the distal end of the plunger 2614 of the ram 2610 contacts the seal 2612, as shown in fig. 27D. In some variations, the initial distance between the distal end of the plunger 2614 and the seal may be between about 1mm to about 10 mm. Once the distal end of the plunger 2614 has contacted the seal 2612, additional distal force on the proximal housing 2624 may be transferred into the distal movement of the plunger 2614 within the syringe cavity 2616. If plunger 2614 moves distally relative to and within syringe cavity 2616, plunger 2614 may push seal 2612 distally relative to and within syringe cavity 2616. This movement of the seal 2612 may reduce the volume of the reservoir 2630 containing the formulation containing the therapeutic or diagnostic agent. Thus, distal movement of the plunger 2614 and, in turn, the seal 2612 relative to and within the syringe cavity 2616 can displace the contents of the reservoir 2630 through the lumen of the needle 2628. When this force is above the necessary force threshold, the distal force on the proximal housing 2624 may continue to displace the contents of the reservoir 2630 through the lumen of the needle 2628 until the seal 2612 has traveled to the distal end of the syringe cavity 2616, at which point the full metered dose of therapeutic or diagnostic agent may have been injected into the patient, as described in more detail above with respect to the injection device 100.

In some variations, once the locking mechanism is unlocked (e.g., the interlocking ring 2634 is displaced), the threshold force required to move the plunger 2614 and seal 2612 distally within the syringe cavity 2616 can be governed by the force assembly 2606. As described above with respect to the injection device 100, the force assembly 2606 may include a stored energy source and a rate control assembly. The stored energy source may be configured to displace the contents of the reservoir 2630 of the syringe 2604 by causing distal movement of the plunger 2614 and seal 2612 within the syringe cavity 2616. The rate control assembly may include a brake assembly that may limit or inhibit displacement of the contents of the reservoir 2630 of the syringe 2604 by the stored energy source.

In the injection device 2600, the stored energy source can include a stored energy spring 2652 (e.g., a compression spring). The energy storage spring 2652 may be attached directly or indirectly to or in contact with a first surface fixed relative to the injector 2604 at one end and attached directly or indirectly to or in contact with a second surface fixed relative to the plunger 2614 of the ram 2610 at the other end. Thus, the force on the first and second surfaces from the stored energy spring 2652 may bias the first and second surfaces away from each other, which in turn may bias the plunger 2614 distally relative to the syringe cavity 2616. In the variation shown in fig. 26 and 27A-27H, a stored energy spring 2652 can be located within the ram housing 2636 and around the plunger 2614 of the ram 2610. Ram housing 2636 may be located proximal to and fixed relative to syringe 2604. Energy storage spring 2652 may be configured to fit within syringe cavity 2616 when energy storage spring 2652 is in an extended configuration. A spring sleeve 2654 may be located between the power spring 2652 and the plunger 2614 of the ram 2610. In the variation shown in fig. 27A-27H, a proximal end of energy storage spring 2652 may be attached to a proximal lip 2656 attached to ram housing 2636, while a distal end of energy storage spring 2652 may be attached or connected proximal to a widened distal portion 2642 of plunger 2614.

Energy storage spring 2652 may be made of any suitable material, such as, but not limited to, steel wire, stainless steel, and spring steel. The spring rate of stored energy spring 2652 may be selected to deliver the appropriate force based on formulation viscosity, needle selection, volume, and desired injection time as described above. In some variations, for example, the stored energy spring 2652 may be configured to transmit a force of up to about 5N, about 10N, about 15N, about 20N, about 25N, about 30N, about 35N, about 40N, about 45N, about 50N, about 55N, about 60N, about 65N, about 70N, about 75N, about 80N, about 85N, or about 90N when initially beginning to expand.

As described above, the rate control assembly of the power assembly 2606 may slow, limit, or inhibit the force provided by the stored energy source to displace the contents of the reservoir 2630 of the syringe 2604. In the injection device 2600, the rate control assembly can include a friction-based braking assembly. The rate control assembly may have a closed configuration in which friction from the rate control assembly may counteract or partially or completely resist the force from the stored energy source. The rate control assembly may also have an open configuration in which there is no frictional force against the stored energy source, or the frictional force resists the stored energy source but is less than the force required to completely prevent the stored energy source from acting on the plunger 2614.

In the variation of fig. 26, the brake assembly may include one or more brake pads 2658 that may be attached to the outer surface of the plunger 2614. The portion of the plunger 2614 that includes the brake pads 2658 may be hollow and flexible such that outward forces from within the plunger 2614 may cause the brake pads 2658 to flex radially outward. For example, the brake pads 2658 may be located on bent portions 2674 of the plunger 2614 that are configured to bend radially outward. The bent portion 2684 is more clearly seen in fig. 30, which shows a perspective view of the ram 2610 in fig. 30. Brake pad 2658 may comprise any suitable material configured to form a high friction interface with spring sleeve 2654. For example, the brake pad 2658 may comprise an elastomer (e.g., rubber, thermoplastic elastomer) that may form a high friction interface with a metal spring sleeve. If an outward force from within the plunger 2614 presses the brake pad 2658 radially outward (e.g., by bending the bent portion 2674 outward) into the spring sleeve 2654, friction between the brake pad 2658 and the spring sleeve 2654 may develop or increase. In some variations, the brake assembly may include two brake pads 2658 (e.g., located on two diametrically opposed bend portions 2674 of the plunger 2614). However, in other variations, the brake assembly may include fewer (e.g., one) or more (e.g., three, four, five, six, or more) brake pads 2658, although it should be appreciated that in some instances it may be desirable for the radial loads generated by the brake pads to be radially symmetric so as to avoid an subtended radial load.

As shown in fig. 27A-27H, in one variation, the outward force on the brake pads 2658 may be achieved by wedge stops 2660. The stop 2660 may be located at a distal end of the rod 2648, which, as described above, may be slidably located within the hollow proximal portion of the plunger 2614. The hollow proximal portion of the plunger 2614 may have a corresponding conical or wedge-shaped internal shape located near or adjacent to the brake pad 2658. When the rate control assembly is in the closed configuration, the stop 2660 can exert a proximal force against the plunger 2614. This proximal force may proximally press the stop 2660 against the corresponding wedge-shaped interior of the plunger 2614, thereby bending the brake pad 2658 outward. When the brake pad 2658 is located adjacent to the spring sleeve 2654, this may generate enough friction to resist the stored energy source (i.e., the rate control assembly may be in the closed configuration). In contrast, when the stop 2660 is not pressed proximally against the interior of the corresponding wedge of the plunger 2614 and thus the brake pad 2658 is not bent outward, friction between the brake pad 2658 and the spring sleeve 2654 may be reduced or eliminated such that a stored energy source (e.g., the energy storage spring 2652) may act on the plunger 2614 (i.e., the rate control assembly may be in an open configuration).

In some variations, the stop 2660 can be biased proximally relative to the plunger 2614 such that the stop 2660 is biased toward a configuration in which it presses proximally against an interior surface of the plunger 2614 such that the rate control assembly is in a closed configuration. The proximal bias may be generated by a biasing element configured to bias the end cap 2650 of the proximal housing 2624 and the plunger 2614 away from each other. As described above, the rod 2648 may be fixedly attached at its proximal end to the end cap 2650 of the proximal housing 2624, while the distal end of the rod 2648 may extend through the open proximal end of the hollow plunger 2614 such that the rod 2648 may slide within the plunger 2614 within a limited range of motion. As shown in fig. 27A-27H, in one variation, the biasing element can include a compression spring 2664 having a proximal end fixed relative to the rod 2648 (e.g., attached at a distal end to an inner surface of the end cap 2650) and a distal end fixed relative to the ram 2610. When a distal force is not applied to the proximal housing 2624, the stop 2660 may thus be naturally biased proximally against the interior of the plunger 2614, thereby pressing the brake pad 2658 outward. In contrast, when sufficient distal force is applied to the proximal housing 2624 to overcome the biasing element, the stop 2660 may not press against the interior of the plunger 2614 and thus the brake pad 2658 may not be squeezed outward such that the rate control assembly is in the open configuration.

When the brake pads 2658 are positioned adjacent to surfaces with which they are configured to form a high friction interface (e.g., spring sleeve 2654), outward flexing of the brake pads 2658 toward the adjacent surfaces may generate friction. This friction may be sufficient to resist the stored energy source (e.g., stored energy spring 2652) such that plunger 2614 and seal 2612 do not move distally within syringe cavity 2616 and an injection is not performed. In contrast, when the brake pads 2658 are located near the surface with which they are configured to form a high friction interface (e.g., spring sleeve 2654) but the brake pads 2658 do not flex outward, there may be no friction; or the friction force may be low enough that a stored energy source (e.g., a stored energy spring 2652) may act on plunger 2614 to move plunger 2614 and seal 2612 distally within syringe cavity 2616 to cause an injection to occur.

In some variations, the frictional force generated at the high friction interface (e.g., between the brake pad 2658 and the spring sleeve 2654) may be at least 2 times the force generated by the biasing element (e.g., compression spring 2664). In some variations, the frictional force generated at the high friction interface may be at least 3 times the force generated by the biasing element. In some variations, the frictional force generated at the high friction interface may be at least 5 times the force generated by the biasing element. In some variations, the frictional force generated at the high friction interface may be at least 10 times the force generated by the biasing element. Accordingly, in these variations, the brake pad may resist movement of the plunger when the force of the stored energy spring is 2, 3, 5 or 10 times greater than the biasing element. For example, in one variation, the energy storage spring 2652 may apply an initial force of about 15N in the compressed configuration, while the biasing element may comprise a compression spring 2664 configured to apply a force of about 7N-8N.

As shown in fig. 27A-27C, a brake pad 2658 may be located proximal to the proximal end of the spring sleeve 2654 before the plunger 2614 and seal 2612 have been advanced into the syringe cavity 2616. In this position, the brake pad 2658 may not be adjacent to another surface and thus may not generate any friction. Thus, after the interlocking ring 2634 is displaced to allow distal movement of the plunger 2614, the energy storage spring 2652 may initially act non-subtendly on the plunger 2614, thereby moving the plunger 2614 distally until the brake pad 2658 enters the spring sleeve 2654. In some variations, this may allow the initial space between plunger 2614 and seal 2612 to close quickly due to the distal movement of plunger 2614. In some variations, it may also be desirable for brake pad 2658 not to be located near spring sleeve 2654 or another surface in the initial state, in order to avoid the brake pad experiencing a compression set. The brake pad 2658 may thus enter the spring sleeve 2654 immediately after the injection begins.

Additional distal force applied to the proximal housing 2624 may advance the plunger 2614 and seal 2612 distally within the syringe cavity 2616, thereby initiating expression of the contents of the reservoir 2630 through the lumen of the needle 2628. As the plunger 2614 and seal 2612 move distally, as shown in fig. 27E, the brake pad 2658 may correspondingly move distally relative to the spring sleeve 2654. When no distal force is applied to the proximal housing 2624 (or when the distal force is below a threshold), the proximal bias on the stopper 2660 may be sufficient to resist the energy storage spring 2652, thereby stopping the injection. When, instead, sufficient distal force is applied to the proximal housing 2624 to overcome the proximal bias on the stopper 2660, the rate control assembly can be in the open configuration (e.g., the brake pad 2658 can not be pressed radially outward by the stopper 2660) and the energy storage spring 2652 can apply a force to push the plunger 2614 and the seal 2612 distally within the reservoir 2630 of the syringe 2604. As shown in fig. 27E, the energy storage spring 2652 may press against the proximal side of the widened region 2642 at the distal end of the plunger 2614. As the energy storage spring 2652 expands during injection, the energy storage spring 2652 may extend into the syringe cavity 2616.

After the plunger 2614 and seal 2612 have begun to advance within the syringe cavity 2616, the brake pad 2658 may be moved distally to rest adjacent to the inner surface of the spring sleeve 2654, as shown in fig. 27E. Thus, the rate control assembly may be reversibly and selectively moved between the open and closed configurations by applying a distal force to the proximal housing 2624. The rate control assembly may move to the open configuration when a distal force is applied to the proximal housing 2624 while the distal end of the injection device 2600 is held in place (e.g., by pressing the distal end of the injection device 2600 against the tissue of the patient). More specifically, the distal force may overcome the bias of the compression spring 2664. As a result, the rod 2648 and the stop 2660 can move distally relative to the plunger 2614, which in turn can remove outward pressure on the brake pad 2658 and reduce friction between the brake pad 2658 and the spring sleeve 2654. This, in turn, may allow the energy storage spring 2652 to act on the plunger 2614 to drive the seal 2612 distally, thereby displacing the contents of the reservoir 2630 through the lumen of the needle 2628. If the distal force on the proximal housing 2624 is released, the bias of the rate control assembly toward the closed configuration may stop the injection. When the distal force is released, the biasing force on the ram 2610 and the stop 2660 may cause them to move proximally relative to the plunger 2614, thereby applying an outward force on the brake pad 2658. As a result, friction between the brake pad 2658 and the spring sleeve 2654 may resist the force of the stored energy source.

It should be appreciated that in this configuration, the force applied to the proximal housing 2624 is also applied to the plunger 2614. That is, the resultant force of the movement of the seal 2612 distally within the syringe cavity 2616 includes both the force of the user and the force generated by the stored energy source (e.g., the stored energy spring 2652). This may allow the user to increase the speed of the injection process beyond the maximum speed produced by the stored energy source alone. Similarly, the user may slow the injection process by applying sufficient distal force to partially, but not fully, open the rate control assembly (e.g., to reduce, but not eliminate, friction between the brake pad 2658 and the spring sleeve 2654). Thus, the user can selectively and reversibly start and stop the injection process or increase or decrease its speed. Fig. 31 shows an illustrative graph of user force required to perform an injection using an injection device having a force assembly similar to force assembly 2606 of injection device 2600. As shown, in one variation, the required user force is about 10N with the force assembly (denoted "assist") and about 23N without the force assembly (denoted "baseline"). Thus, the device may have a force multiplication factor of about 2.3. It should be noted that this graph illustrates only the required user force for a similar device and is not meant to indicate that the injection device 2600 may or must be in accordance with this representation.

In some variations, the injection device 2600 may include an auto-completion mechanism that can automatically displace the entire volume of the reservoir 2630 through the lumen of the needle 2628 within certain tolerances of a full injection (e.g., within about 85% of an injection, within about 90% of an injection, within about 95% of an injection, or more, or within about 1mm of a full displacement, about 2mm of a full displacement, about 3mm of a full displacement, or about 4mm of a full displacement, etc.) regardless of the distal force applied by the user to the proximal housing 2624. In some variations, auto-completion may be caused by brake pad 2658 no longer contacting spring sleeve 2654. For example, when the seal 2612 is located near the distal end of the syringe cavity 2616, the plunger 2614 may have traveled distally within the syringe cavity 2616 so that the brake pad 2658 may reach the distal end of the spring sleeve 2654. When the brake pads 2658 move distally beyond the spring sleeves 2654, they may no longer be in contact with the spring sleeves 2654. Accordingly, there may be no friction between the brake pad 2658 and the spring sleeve 2654, and thus no force against the distal force from the energy storage spring 2652. As a result, the dose may be automatically completed due to the distal force on plunger 2614 from energy storage spring 2652.

The injection device 2600 may also include an indicator, as described with respect to the injection device 100, that may indicate the progress or completion of an injection and may have an activated configuration and an inactivated configuration. In some variations of the injection device 2600, the indicator may include a metering tip indicator 2618 to alert a user that a full dose has been displaced from the reservoir 2630 of the syringe 2604 and/or that the seal 2612 has traveled the full length of the reservoir 2630 to the distal end of the syringe cavity 2616. Additionally or alternatively, the dose tip indicator 2618 can alert a user that the entire dose has been displaced (e.g., greater than or equal to about 85%, greater than or equal to about 90%, greater than or equal to about 95%, or more) and/or that the seal 2612 has moved proximate (e.g., greater than or equal to about 85%, greater than or equal to about 90%, greater than or equal to about 95%, or more, or within about 1mm of full displacement, about 2mm of full displacement, about 3mm of full displacement, or about 4mm of full displacement, etc.) the full length of the reservoir 2630 to the distal end of the syringe cavity 2616. In variations of the injection device having both an auto-complete mechanism and a dose tip indicator, these may be triggered simultaneously. This may reduce the likelihood that the user will not be able to deliver a full dose if the dose tip indicator is deployed before the dose has been completely delivered.

The dose tip indicator 2618 may have different appearances in relation to the unactivated configuration and the activated configuration. Fig. 27A-27E illustrate the dose tip indicator 2618 in an unactivated configuration, while fig. 27F-27H illustrate the dose tip indicator 2618 in an activated configuration. The dose tip indicator 2618 is visible through the housing in the activated configuration and is not visible through the housing in the inactivated configuration.

In the variation shown in fig. 27A-27H, the end cap 2650 of the proximal housing 2624 can be configured such that, when the dose tip indicator 2618 is adjacent to the inner surface of the end cap 2650, at least a portion of the dose tip indicator 2618 is visible from the exterior of the end cap 2650 through the viewing portion. In some variations, at least a portion of the dose tip indicator 2618 may have a color or pigment that is more readily noticeable, such as, but not limited to, red, yellow, orange, green, magenta, blue, and the like. To see the dose tip indicator 2618 through at least a portion of the end cap 2650, in some variations, at least a portion of the end cap 2650 may be translucent. In a variation where a portion of the end cap 2650 is translucent, the degree of translucency may be such that the coloration of the dose tip indicator 2618 is only perceptible through the end cap 2650 when the dose tip indicator 2618 is adjacent or near adjacent to the viewing portion. In other variations, the end cap 2650 may include a portion configured such that the dose tip indicator is not visible in the unactivated configuration, and the dose tip indicator 2618 is only visible through the viewing portion when the dose tip indicator 2618 is adjacent to a transparent or open region, e.g., due to a viewing angle. For example, in some such variations, the viewing portion may include a transparent region around the circumference of the end cap 2650, and the dose tip indicator 2618 may only be visible through the viewing portion when aligned near the viewing portion. The dose tip indicator 2618 can include a lumen therethrough such that the dose tip indicator 2618 fits within the proximal housing 2624 and around the ram housing 2636.

The biasing element may be configured to bias the dose tip indicator 2618 toward the activated configuration. The biasing element may have a compressed configuration and an expanded configuration. The biasing element can be in a compressed configuration when the dose tip indicator 2618 is in an unactuated configuration and the biasing element can be in an expanded configuration when the dose tip indicator 2618 is in an actuated configuration. In some variations, the biasing element may include a compression spring 2666. A proximal end of the compression spring 2666 may be connected or in contact with the dose tip indicator 2618 and a distal end of the compression spring 2666 may be connected or in contact with an object, such as an interlocking ring 2634 (described above), located distal to the dose tip indicator 2618. The biasing element may thus bias the dose tip indicator 2618 toward the proximal end of the proximal housing 2624.

As shown in fig. 27A-27E, the ram housing 2636 can include one or more latches 2670 that can retain the dose tip indicator 2618 in an activated configuration prior to release. The latches 2670 each can include a radially outwardly extending lip that can press distally against a proximal surface of the dose tip indicator 2618. The lip may prevent the biasing force from the biasing element (e.g., compression spring 2666) from tending to urge the dose tip indicator 2618 toward the activated configuration. When the dose tip indicator 2618 is released from the latch 2670, the indicator may no longer be held in the activated configuration. The dose tip indicator 2618 may be released by a radially inward force on the latches 2670. In the variation shown in fig. 27A-27H, the radially inward force may be applied by a portion of the end cap 2650. As shown in fig. 27E, the end cap 2650 can include a rim 2672 extending distally from an interior of the end cap 2650, which in some variations can have a cup shape as shown. End cap 2650 is moved distally relative to latch 2670 and ram housing 2636 during an injection, and edge 2672 may contact the ramped portion of latch 2670, as shown in fig. 27F. This may create a radially inward force on latch 2670. The latches 2670 can thus flex inward, releasing the radially outwardly extending lips from the proximal surface of the dose tip indicator 2618. The ram housing 2636 may include any suitable number of latches 2670, such as, but not limited to, one, two, three, four, five, six, or more. Rim 2672 may have any suitable corresponding configuration, such as, but not limited to, a continuous cup shape, or individual arms each configured to contact latch 2670. Once released, the biasing force from the compression spring 2666 can move the dose tip indicator 2618 proximally toward an activated configuration, as shown in fig. 27F-27H. In some variations, the dose tip indicator 2618 may be configured to produce an abrupt audible and/or tactile indication that the full or nearly full dose has been delivered.

After the injection is complete, the injection device 2600 may be removed from the patient. When the proximal force on the shield 2620 of the needle safety assembly 2622 from the tissue is removed, a biasing element (e.g., compression spring 2662) may return the needle shield 2620 to the extended configuration. In some variations, the shield 2620 of the needle safety assembly 2622 may additionally or alternatively be configured to be locked in the extended configuration after being moved from the retracted configuration to the extended configuration. This feature may limit the ability of the needle 2628 to protrude from the distal end of the nose to pierce or otherwise contact tissue or other surfaces after the injection device 2600 has been removed from the patient's tissue. This may make the injection device 2600 safer for the user and/or patient by limiting inadvertent needle sticks. It should be appreciated that, in some variations, the needle safety assembly 2622 may be brought into a locked, extended configuration if the injection device 2600 is removed from the patient before the injection has been fully completed.

Fig. 28A-28C illustrate a variation of a mechanism that may be used to initially retract the needle safety assembly 2622 by a proximal force on the shield 2620, but after having been retracted, the needle safety assembly 2622 may lock it in the extended configuration. Needle safety assembly 2622 may include a shield lock ring 2668, which is shown isolated in fig. 29C. Shield lock ring 2668 may be located between a proximal portion of needle safety assembly 2622 and distal housing 2632. The cover lock ring 2668 is movable between three configurations: a first, stable configuration of needle safety assembly 2622 when initially extended; a second, unstable configuration when needle safety assembly 2622 is retracted; and a third, stable configuration of needle safety assembly 2622 when extended after having been retracted. The initial stable configuration is shown in fig. 28A. As needle safety assembly 2622 is moved toward the retracted configuration shown in fig. 28B, proximal movement of the proximal end of needle safety assembly 2622 may rotate shield lock ring 2668 into a second, unstable configuration. As the needle safety assembly 2622 is moved back toward the retracted configuration shown in fig. 28C, distal movement of the proximal end of the needle safety assembly 2622 may rotate the shield lock ring 2668 into the third, stable configuration. Once the shield lock ring 2668 has entered the third, stable configuration, it may prevent distal movement of the needle safety assembly 2622.

More specifically, when needle safety assembly 2622 is initially in the extended position, shield lock ring 2668 may be seated against an internal shoulder of distal housing 2632 in a first, stable configuration and may be biased proximally towards the internal shoulder by compression spring 2662. Inner shoulders of shield lock ring 2668 and distal housing 2632 may include sloped surfaces such that shield lock ring 2668 may seat against the inner shoulders in two different stable positions. As the needle safety assembly 2622 is retracted, the angled surfaces 2680 on each arm 2644 of the needle safety assembly 2622 may move into contact with the tabs 2684 of the shield ring 2668. As the needle safety assembly 2622 and the arms 2644 move proximally, this may exert a force on the tabs 2684 that may rotate the shield lock ring 2668 (e.g., between about 10 degrees and about 30 degrees, about 15 degrees, or any suitable range). During this motion, the cover lock ring 2668 may move distally relative to the inner shoulder of the distal housing 2632, allowing the cover lock ring 2668 to rotate over the peaks formed by the sloped surfaces of the inner shoulder. After the cover lock ring 2668 rotates past the peak, the compression spring 2662 may bias the cover lock ring 2682 rearwardly against an internal shoulder of the distal housing 2632. Once the needle safety assembly 2622 is in the fully retracted position, steps 2686 on the needle safety assembly 2622 may interface with tabs 2684 to prevent further rotation of the shield ring 2668. When needle safety assembly 2622 is moved back toward the retracted configuration after having been in the retracted position, needle safety assembly 2622 may disengage from cover lock ring 2682, and cover lock ring 2682 may also rotate under the bias from compression spring 2662 until it reaches a second, stable configuration against the inner shoulder of distal housing 2632. In this configuration, further rotation of the shield lock ring 2668 may be prevented by tabs 2688 on the needle safety assembly 2622, but further retraction of the needle safety assembly 2622 is prevented.

While the variations of the injection device just described above are configured to lock in the extended configuration after having been in the retracted configuration, it should be appreciated that in other variations, the needle shield may not be configured to lock when reentering the extended position (e.g., in some variations, the needle shield may continue to be able to retract from the extended position in response to a distal force).

In some variations, one or more of the elements of the injection device 2600 may optionally include a blocking feature to properly orient the elements relative to each other, as described above with respect to the injection device 100.

Although embodiments have been described and illustrated herein, these embodiments are provided by way of example only. Variations, modifications, and substitutions may be made without departing from the embodiments provided by way of example. It should be noted that various alternatives to the exemplary embodiments described herein may be employed.

Claims (28)

1. A device for injecting a formulation, comprising:

a syringe comprising a syringe cavity, a plunger element slidably received in the syringe cavity, and a hollow needle in fluid communication with the syringe cavity, wherein the plunger element is configured to move from a proximal position to a distal position;

A force assembly configured to transmit force to the plunger element; and

a user-actuated brake assembly configured to reversibly resist movement of the plunger element in at least one intermediate position between the proximal and distal positions, wherein the user-actuated brake assembly comprises at least one brake pad attached to an outer surface of the plunger, the brake pad configured to resist movement of the plunger element by moving radially outward.

2. The device of claim 1, wherein the brake assembly is biased to prevent movement of the plunger element when in an inactivated state and to allow movement of the plunger element when in an activated state.

3. The device of claim 2, wherein the brake assembly is biased by a brake spring to resist movement of the plunger element.

4. The device of any one of claims 1 to 3, wherein the force assembly comprises a mechanical spring.

5. The device of any one of claims 1-3, wherein the plunger element is further configured to simultaneously receive a user-applied force that moves the plunger element toward the distal position.

6. The device of any one of claims 1 to 3, further comprising a housing, wherein the syringe is located in the housing.

7. The device of claim 6, wherein the housing is coupled with the plunger element.

8. The device of claim 7, wherein the housing is configured to transmit a user-applied force to the plunger element.

9. The device of claim 6, wherein the syringe is slidably located in the housing and the syringe is configured to move from a retracted position in which the distal tip of the needle is located within the housing to an extended position in which the distal tip of the needle extends distally of the housing.

10. The device of claim 9, further comprising an extendable needle shield, wherein the needle shield is configured to have a releasably locked retracted state relative to the syringe and an unlocked state that allows movement toward the extended position relative to the syringe, and wherein the needle shield is further configured to switch to the unlocked state before the distal tip of the needle extends distally of the housing.

11. The device of any one of claims 1 to 3, wherein the brake assembly acts on a surface fixed relative to the syringe to reversibly resist movement of the plunger element.

12. The device of any one of claims 1-3, wherein the force assembly is configured to pull the plunger element toward the distal position.

13. The device of any one of claims 1-3, wherein the force assembly is configured to urge the plunger element toward the distal position.

14. The device of claim 13, wherein the power assembly is further configured to push and pull the plunger element toward the distal position.

15. The device of any one of claims 1 to 3, further comprising an extendable needle shield, wherein the needle shield is configured to have a releasably locked retracted state relative to the syringe and an unlocked state allowing movement towards an extended position relative to the syringe.

16. The device of claim 15, wherein the needle shield is further configured to relock when the needle shield reaches the extended state.

17. The device of any one of claims 1 to 3, further comprising an extendable needle shield, wherein the needle shield is configured to have an unlocked extended state and a locked extended state, the unlocked extended state allowing movement relative to the syringe toward a retracted position.

18. The device of claim 17, wherein the needle shield is configured to enter the locked extended state when the needle shield is extended from the retracted state.

19. A device for injecting a formulation, the device comprising: a syringe comprising a syringe cavity; a housing, wherein the syringe is located in the housing; a plunger slidably received in the syringe cavity; and a hollow needle in fluid communication with the syringe cavity; wherein the plunger is configured to move from a proximal position to a distal position; a force assembly configured to transmit force to the plunger; and a user-actuated brake assembly configured to reversibly resist movement of the plunger in at least one intermediate position between the proximal and distal positions, wherein the user-actuated brake assembly comprises at least one brake pad attached to an outer surface of the plunger, the brake pad configured to resist movement of the plunger element by moving radially outward, and wherein the device is configured to:

receiving a force applied to the housing, wherein the force causes the force assembly to transmit force to the plunger to move the plunger toward the distal position; and

Wherein reducing the applied force when the plunger is in the intermediate position causes the brake assembly to reduce the force transmitted to the plunger by the force assembly.

20. The device of claim 19, wherein the housing comprises a proximal housing and a distal housing, and wherein applying force to the housing comprises applying a distal force to the proximal housing.

21. The device of claim 19, wherein application of force to the housing further moves the brake assembly from an unactuated state to an actuated state, wherein the brake assembly is biased to prevent movement of the plunger when in the unactuated state and allows movement of the plunger element when in the actuated state.

22. The device of any one of claims 19-21, further comprising re-applying force to the housing, wherein re-applying force to the housing causes the force applicator assembly to transmit force to the plunger to move the plunger toward the distal position.

23. A device for injecting a formulation, comprising:

a housing having a longitudinal axis;

a syringe containing the formulation within a syringe cavity, wherein the syringe is located within the housing;

A plunger slidable within the syringe, the plunger configured to be movable between a proximal position and a distal position, wherein moving the plunger toward the distal position displaces the formulation from the syringe; and

a spring in contact with the plunger, the spring configured to bias the plunger toward the distal position,

wherein the plunger comprises a brake pad attached on an outer surface of the plunger, the brake pad configured to be reversibly movable between a first configuration and a second configuration by moving radially outward, wherein the brake pad generates friction in the second configuration to resist movement of the plunger.

24. The device of claim 23, further comprising a stopper located within the plunger and movable within the plunger between a proximal position and a distal position, wherein the stopper is configured such that movement of the stopper from the distal position to the proximal position causes the brake pad to move from the first configuration to the second configuration.

25. The device of claim 24, wherein the stop is biased toward the proximal position.

26. The device of claim 24 or 25, wherein the stopper is configured to be movable between the proximal position and the distal position by application of a distal force on the housing.

27. The device of claim 23 or 24, further comprising a retractable needle shield configured to be movable between a retracted position and an extended position.

28. The device of claim 23 or 24, further comprising a dose tip indicator movable between an unactuated configuration and an actuated configuration.

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